"""MCP client: connects to MCP servers and wraps their tools as native nanobot tools.""" import asyncio import json import os import re import shutil import urllib.parse from collections.abc import Awaitable, Callable from contextlib import AsyncExitStack, suppress from typing import Any, Mapping from weakref import WeakKeyDictionary import httpx from loguru import logger from nanobot.agent.tools.base import Tool from nanobot.agent.tools.registry import ToolRegistry from nanobot.bus.events import ( INBOUND_META_RUNTIME_CONTROL, RUNTIME_CONTROL_ACK, RUNTIME_CONTROL_MCP_RELOAD, InboundMessage, ) from nanobot.security.network import validate_url_target # Transient connection errors that warrant a single retry. # These typically happen when an MCP server restarts or a network # connection is interrupted between calls. _TRANSIENT_EXC_NAMES: frozenset[str] = frozenset(( "ClosedResourceError", "BrokenResourceError", "EndOfStream", "BrokenPipeError", "ConnectionResetError", "ConnectionRefusedError", "ConnectionAbortedError", "ConnectionError", )) _WINDOWS_SHELL_LAUNCHERS: frozenset[str] = frozenset(("npx", "npm", "pnpm", "yarn", "bunx")) # Characters allowed in tool names by model providers (Anthropic, OpenAI, etc.). # Replace anything outside [a-zA-Z0-9_-] with underscore and collapse runs. _SANITIZE_RE = re.compile(r"_+") _RELOAD_LOCKS: WeakKeyDictionary[Any, asyncio.Lock] = WeakKeyDictionary() _ReconnectCallback = Callable[[str, str, Tool], Awaitable[Tool | None]] def _is_malformed_mcp_progress_notification(message: Any) -> bool: payload = _mcp_jsonrpc_payload(message) if _payload_value(payload, "method") != "notifications/progress": return False params = _payload_value(payload, "params") return not _progress_params_have_token(params) def _mcp_jsonrpc_payload(message: Any) -> Any: """Return the JSON-RPC payload across current and future MCP SDK shapes.""" envelope = getattr(message, "message", message) return getattr(envelope, "root", None) or envelope def _payload_value(payload: Any, key: str) -> Any: if isinstance(payload, Mapping): return payload.get(key) return getattr(payload, key, None) def _progress_params_have_token(params: Any) -> bool: if isinstance(params, Mapping): return "progressToken" in params return hasattr(params, "progressToken") or hasattr(params, "progress_token") class _MalformedProgressNotificationFilter: def __init__(self, read_stream: Any, server_name: str) -> None: self._read_stream = read_stream self._server_name = server_name self._iterator: Any | None = None async def __aenter__(self) -> "_MalformedProgressNotificationFilter": await self._read_stream.__aenter__() return self async def __aexit__(self, exc_type: Any, exc: Any, tb: Any) -> Any: return await self._read_stream.__aexit__(exc_type, exc, tb) def __aiter__(self) -> "_MalformedProgressNotificationFilter": self._iterator = self._read_stream.__aiter__() return self async def __anext__(self) -> Any: if self._iterator is None: self._iterator = self._read_stream.__aiter__() while True: message = await self._iterator.__anext__() if _is_malformed_mcp_progress_notification(message): logger.debug( "MCP server '{}': dropped progress notification without progressToken", self._server_name, ) continue return message async def aclose(self) -> None: close = getattr(self._read_stream, "aclose", None) if close is not None: await close() def _filter_malformed_mcp_progress_notifications(read_stream: Any, server_name: str) -> Any: if not all(hasattr(read_stream, name) for name in ("__aenter__", "__aexit__", "__aiter__")): return read_stream return _MalformedProgressNotificationFilter(read_stream, server_name) def _sanitize_name(name: str) -> str: """Sanitize an MCP-derived name for model API compatibility.""" return _SANITIZE_RE.sub("_", re.sub(r"[^a-zA-Z0-9_-]", "_", name)) def _is_transient(exc: BaseException) -> bool: """Check if an exception looks like a transient connection error.""" return type(exc).__name__ in _TRANSIENT_EXC_NAMES def _is_session_terminated(exc: BaseException) -> bool: """Return True when the MCP SDK reports a dead client session.""" messages = [str(exc)] error = getattr(exc, "error", None) if error is not None: messages.append(str(getattr(error, "message", ""))) return any( marker in message.lower() for marker in ("session terminated", "connection closed") for message in messages ) async def _probe_http_url(url: str, timeout: float = 3.0) -> bool: """Quick TCP probe to check if an HTTP MCP server is reachable. Avoids entering ``streamable_http_client`` / ``sse_client`` when the port is closed — those transports use anyio task groups whose cleanup can raise ``RuntimeError`` / ``ExceptionGroup`` that escape the caller's try/except and crash the event loop. """ parsed = urllib.parse.urlparse(url) host = parsed.hostname or "127.0.0.1" port = parsed.port if not port: port = 443 if parsed.scheme == "https" else 80 try: reader, writer = await asyncio.wait_for( asyncio.open_connection(host, port), timeout=timeout, ) writer.close() with suppress(OSError, asyncio.TimeoutError): await asyncio.wait_for(writer.wait_closed(), timeout=0.2) return True except (OSError, asyncio.TimeoutError): return False def _redact_url(url: str) -> str: """Strip credentials and query/fragment before logging an MCP URL. Server URLs may embed secrets (``https://user:token@host/sse`` or a ``?token=`` query). Some deployments also put opaque tokens in the path, so log only the origin and a path placeholder. """ try: parts = urllib.parse.urlsplit(url) hostname = parts.hostname or "" netloc = f"[{hostname}]" if ":" in hostname else hostname if parts.port: netloc = f"{netloc}:{parts.port}" path = "/..." if parts.path and parts.path != "/" else parts.path return urllib.parse.urlunsplit((parts.scheme, netloc, path, "", "")) except Exception: return "" async def _validate_mcp_request_url(request: httpx.Request) -> None: """Validate each outgoing MCP HTTP request, including redirect targets.""" ok, error = validate_url_target(str(request.url)) if not ok: raise httpx.RequestError( f"Blocked unsafe MCP URL {_redact_url(str(request.url))} ({error})", request=request, ) def _windows_command_basename(command: str) -> str: """Return the lowercase basename for a Windows command or path.""" return command.replace("\\", "/").rsplit("/", maxsplit=1)[-1].lower() def _normalize_windows_stdio_command( command: str, args: list[str] | None, env: dict[str, str] | None, ) -> tuple[str, list[str], dict[str, str] | None]: """Wrap Windows shell launchers so MCP stdio servers start reliably.""" normalized_args = list(args or []) if os.name != "nt": return command, normalized_args, env basename = _windows_command_basename(command) if basename in {"cmd", "cmd.exe", "powershell", "powershell.exe", "pwsh", "pwsh.exe"}: return command, normalized_args, env if basename.endswith((".exe", ".com")): return command, normalized_args, env resolved = shutil.which(command, path=(env or {}).get("PATH")) or command resolved_basename = _windows_command_basename(resolved) should_wrap = ( basename in _WINDOWS_SHELL_LAUNCHERS or basename.endswith((".cmd", ".bat")) or resolved_basename.endswith((".cmd", ".bat")) ) if not should_wrap: return command, normalized_args, env comspec = (env or {}).get("COMSPEC") or os.environ.get("COMSPEC") or "cmd.exe" return comspec, ["/d", "/c", command, *normalized_args], env def _extract_nullable_branch(options: Any) -> tuple[dict[str, Any], bool] | None: """Return the single non-null branch for nullable unions.""" if not isinstance(options, list): return None non_null: list[dict[str, Any]] = [] saw_null = False for option in options: if not isinstance(option, dict): return None if option.get("type") == "null": saw_null = True continue non_null.append(option) if saw_null and len(non_null) == 1: return non_null[0], True return None def _normalize_schema_for_openai(schema: Any) -> dict[str, Any]: """Normalize only nullable JSON Schema patterns for tool definitions.""" if not isinstance(schema, dict): return {"type": "object", "properties": {}} normalized = dict(schema) raw_type = normalized.get("type") if isinstance(raw_type, list): non_null = [item for item in raw_type if item != "null"] if "null" in raw_type and len(non_null) == 1: normalized["type"] = non_null[0] normalized["nullable"] = True for key in ("oneOf", "anyOf"): nullable_branch = _extract_nullable_branch(normalized.get(key)) if nullable_branch is not None: branch, _ = nullable_branch merged = {k: v for k, v in normalized.items() if k != key} merged.update(branch) normalized = merged normalized["nullable"] = True break if "properties" in normalized and isinstance(normalized["properties"], dict): normalized["properties"] = { name: _normalize_schema_for_openai(prop) if isinstance(prop, dict) else prop for name, prop in normalized["properties"].items() } if "items" in normalized and isinstance(normalized["items"], dict): normalized["items"] = _normalize_schema_for_openai(normalized["items"]) if normalized.get("type") != "object": return normalized normalized.setdefault("properties", {}) normalized.setdefault("required", []) return normalized class _MCPWrapperBase(Tool): """Common reconnect handling for wrappers bound to one MCP server session.""" _plugin_discoverable = False def _set_mcp_connection(self, session: Any, server_name: str) -> None: self._session = session self._server_name = server_name self._reconnect: _ReconnectCallback | None = None def set_reconnect_handler(self, reconnect: _ReconnectCallback) -> None: self._reconnect = reconnect async def _refresh_session_after_termination( self, exc: BaseException, already_refreshed: bool, capability_kind: str, ) -> bool: if already_refreshed or not _is_session_terminated(exc) or self._reconnect is None: return False logger.warning( "MCP {} '{}' session terminated; reconnecting server '{}' before retry", capability_kind, self._name, self._server_name, ) refreshed_tool = await self._reconnect(self._server_name, self._name, self) refreshed_session = getattr(refreshed_tool, "_session", None) if refreshed_session is None: logger.warning( "MCP {} '{}' could not refresh session for server '{}'", capability_kind, self._name, self._server_name, ) return False self._session = refreshed_session return True def _image_block_data_url(block: Any, types: Any) -> str | None: """Return a base64 ``data:`` URL for an MCP image-bearing content block. Handles ``ImageContent`` directly and ``EmbeddedResource`` wrapping a binary blob with an ``image/*`` MIME type. Returns ``None`` for anything else. ``getattr`` guards keep this safe when the installed/faked ``mcp`` SDK does not expose a given type. """ image_cls = getattr(types, "ImageContent", None) if image_cls is not None and isinstance(block, image_cls): mime = getattr(block, "mimeType", None) or "image/png" return f"data:{mime};base64,{block.data}" embedded_cls = getattr(types, "EmbeddedResource", None) blob_cls = getattr(types, "BlobResourceContents", None) if embedded_cls is not None and isinstance(block, embedded_cls): resource = getattr(block, "resource", None) if blob_cls is not None and isinstance(resource, blob_cls): mime = getattr(resource, "mimeType", None) or "" if isinstance(mime, str) and mime.startswith("image/"): return f"data:{mime};base64,{resource.blob}" return None def _mcp_image_tool_result(text_parts: list[str], artifacts: list[dict[str, Any]]) -> str: """Build the compact tool result for an MCP call that returned image(s). The base64 stays out of the model context entirely — only artifact paths and metadata are returned, so the result is small and the channel can deliver the saved file via the message tool. """ payload: dict[str, Any] = { "artifacts": artifacts, "next_step": ( "These images were returned by an MCP tool and saved as local artifacts. " "Call the message tool with the artifact 'path' values in the media " "parameter to deliver the images to the user. Do not paste base64 or raw " "paths into your reply unless the user asks for debug details." ), } text = "\n".join(part for part in text_parts if part) if text: payload["text"] = text return json.dumps(payload, ensure_ascii=False) class MCPToolWrapper(_MCPWrapperBase): """Wraps a single MCP server tool as a nanobot Tool.""" _plugin_discoverable = False def __init__(self, session, server_name: str, tool_def, tool_timeout: int = 30): self._set_mcp_connection(session, server_name) self._original_name = tool_def.name self._name = _sanitize_name(f"mcp_{server_name}_{tool_def.name}") self._description = tool_def.description or tool_def.name raw_schema = tool_def.inputSchema or {"type": "object", "properties": {}} self._parameters = _normalize_schema_for_openai(raw_schema) self._tool_timeout = tool_timeout @property def name(self) -> str: return self._name @property def description(self) -> str: return self._description @property def parameters(self) -> dict[str, Any]: return self._parameters async def execute(self, **kwargs: Any) -> str: retried_transient = False refreshed_session = False while True: try: result = await asyncio.wait_for( self._session.call_tool(self._original_name, arguments=kwargs), timeout=self._tool_timeout, ) except asyncio.TimeoutError: logger.warning( "MCP tool '{}' timed out after {}s", self._name, self._tool_timeout ) return f"(MCP tool call timed out after {self._tool_timeout}s)" except asyncio.CancelledError: # MCP SDK's anyio cancel scopes can leak CancelledError on timeout/failure. # Re-raise only if our task was externally cancelled (e.g. /stop). task = asyncio.current_task() if task is not None and task.cancelling() > 0: raise logger.warning("MCP tool '{}' was cancelled by server/SDK", self._name) return "(MCP tool call was cancelled)" except Exception as exc: if await self._refresh_session_after_termination( exc, refreshed_session, "tool", ): refreshed_session = True continue if _is_transient(exc): if not retried_transient: retried_transient = True logger.warning( "MCP tool '{}' hit transient error ({}), retrying once...", self._name, type(exc).__name__, ) await asyncio.sleep(1) # Brief backoff before retry continue # Second transient failure — give up with retry-specific message logger.exception( "MCP tool '{}' failed after retry: {}", self._name, type(exc).__name__, ) return f"(MCP tool call failed after retry: {type(exc).__name__})" logger.exception( "MCP tool '{}' failed: {}: {}", self._name, type(exc).__name__, exc, ) return f"(MCP tool call failed: {type(exc).__name__})" else: # Success — extract text and persist any image content as artifacts. return self._render_call_result(result.content, kwargs) return "(MCP tool call failed)" # Unreachable, but satisfies type checkers def _render_call_result(self, content: Any, arguments: Mapping[str, Any]) -> str: """Turn MCP content blocks into a tool result string. Text is concatenated as before. Image blocks are decoded and saved as local artifacts (mirroring the built-in image generation tool) so the model can deliver them via the message tool instead of trying to forward base64 — which would be truncated and bloat the context window. """ from mcp import types text_parts: list[str] = [] artifacts: list[dict[str, Any]] = [] for block in content: if isinstance(block, types.TextContent): text_parts.append(block.text) continue data_url = _image_block_data_url(block, types) if data_url is not None: stored = self._store_image_block(data_url, arguments) if stored is not None: artifacts.append(stored) else: text_parts.append("(MCP tool returned an image that could not be stored)") continue text_parts.append(str(block)) if artifacts: return _mcp_image_tool_result(text_parts, artifacts) return "\n".join(text_parts) or "(no output)" def _store_image_block( self, data_url: str, arguments: Mapping[str, Any] ) -> dict[str, Any] | None: """Persist one image data URL as an artifact; return its metadata or None.""" from nanobot.utils.artifacts import ArtifactError, store_generated_image_artifact try: return store_generated_image_artifact( data_url, prompt=str(arguments.get("prompt") or ""), model=str(arguments.get("model") or ""), save_dir="generated", provider=f"mcp:{self._server_name}", ) except (ArtifactError, OSError) as exc: logger.warning( "MCP tool '{}' returned an image that could not be stored: {}", self._name, exc, ) return None class MCPResourceWrapper(_MCPWrapperBase): """Wraps an MCP resource URI as a read-only nanobot Tool.""" _plugin_discoverable = False def __init__(self, session, server_name: str, resource_def, resource_timeout: int = 30): self._set_mcp_connection(session, server_name) self._uri = resource_def.uri self._name = _sanitize_name(f"mcp_{server_name}_resource_{resource_def.name}") desc = resource_def.description or resource_def.name self._description = f"[MCP Resource] {desc}\nURI: {self._uri}" self._parameters: dict[str, Any] = { "type": "object", "properties": {}, "required": [], } self._resource_timeout = resource_timeout @property def name(self) -> str: return self._name @property def description(self) -> str: return self._description @property def parameters(self) -> dict[str, Any]: return self._parameters @property def read_only(self) -> bool: return True async def execute(self, **kwargs: Any) -> str: from mcp import types retried_transient = False refreshed_session = False while True: try: result = await asyncio.wait_for( self._session.read_resource(self._uri), timeout=self._resource_timeout, ) except asyncio.TimeoutError: logger.warning( "MCP resource '{}' timed out after {}s", self._name, self._resource_timeout ) return f"(MCP resource read timed out after {self._resource_timeout}s)" except asyncio.CancelledError: task = asyncio.current_task() if task is not None and task.cancelling() > 0: raise logger.warning("MCP resource '{}' was cancelled by server/SDK", self._name) return "(MCP resource read was cancelled)" except Exception as exc: if await self._refresh_session_after_termination( exc, refreshed_session, "resource", ): refreshed_session = True continue if _is_transient(exc): if not retried_transient: retried_transient = True logger.warning( "MCP resource '{}' hit transient error ({}), retrying once...", self._name, type(exc).__name__, ) await asyncio.sleep(1) continue logger.exception( "MCP resource '{}' failed after retry: {}", self._name, type(exc).__name__, ) return f"(MCP resource read failed after retry: {type(exc).__name__})" logger.exception( "MCP resource '{}' failed: {}: {}", self._name, type(exc).__name__, exc, ) return f"(MCP resource read failed: {type(exc).__name__})" else: parts: list[str] = [] for block in result.contents: if isinstance(block, types.TextResourceContents): parts.append(block.text) elif isinstance(block, types.BlobResourceContents): parts.append(f"[Binary resource: {len(block.blob)} bytes]") else: parts.append(str(block)) return "\n".join(parts) or "(no output)" return "(MCP resource read failed)" # Unreachable class MCPPromptWrapper(_MCPWrapperBase): """Wraps an MCP prompt as a read-only nanobot Tool.""" _plugin_discoverable = False def __init__(self, session, server_name: str, prompt_def, prompt_timeout: int = 30): self._set_mcp_connection(session, server_name) self._prompt_name = prompt_def.name self._name = _sanitize_name(f"mcp_{server_name}_prompt_{prompt_def.name}") desc = prompt_def.description or prompt_def.name self._description = ( f"[MCP Prompt] {desc}\n" "Returns a filled prompt template that can be used as a workflow guide." ) self._prompt_timeout = prompt_timeout # Build parameters from prompt arguments properties: dict[str, Any] = {} required: list[str] = [] for arg in prompt_def.arguments or []: prop: dict[str, Any] = {"type": "string"} if getattr(arg, "description", None): prop["description"] = arg.description properties[arg.name] = prop if arg.required: required.append(arg.name) self._parameters: dict[str, Any] = { "type": "object", "properties": properties, "required": required, } @property def name(self) -> str: return self._name @property def description(self) -> str: return self._description @property def parameters(self) -> dict[str, Any]: return self._parameters @property def read_only(self) -> bool: return True async def execute(self, **kwargs: Any) -> str: from mcp import types from mcp.shared.exceptions import McpError retried_transient = False refreshed_session = False while True: try: result = await asyncio.wait_for( self._session.get_prompt(self._prompt_name, arguments=kwargs), timeout=self._prompt_timeout, ) except asyncio.TimeoutError: logger.warning( "MCP prompt '{}' timed out after {}s", self._name, self._prompt_timeout ) return f"(MCP prompt call timed out after {self._prompt_timeout}s)" except asyncio.CancelledError: task = asyncio.current_task() if task is not None and task.cancelling() > 0: raise logger.warning("MCP prompt '{}' was cancelled by server/SDK", self._name) return "(MCP prompt call was cancelled)" except McpError as exc: if await self._refresh_session_after_termination( exc, refreshed_session, "prompt", ): refreshed_session = True continue logger.exception( "MCP prompt '{}' failed: code={} message={}", self._name, exc.error.code, exc.error.message, ) return f"(MCP prompt call failed: {exc.error.message} [code {exc.error.code}])" except Exception as exc: if await self._refresh_session_after_termination( exc, refreshed_session, "prompt", ): refreshed_session = True continue if _is_transient(exc): if not retried_transient: retried_transient = True logger.warning( "MCP prompt '{}' hit transient error ({}), retrying once...", self._name, type(exc).__name__, ) await asyncio.sleep(1) continue logger.exception( "MCP prompt '{}' failed after retry: {}", self._name, type(exc).__name__, ) return f"(MCP prompt call failed after retry: {type(exc).__name__})" logger.exception( "MCP prompt '{}' failed: {}: {}", self._name, type(exc).__name__, exc, ) return f"(MCP prompt call failed: {type(exc).__name__})" else: parts: list[str] = [] for message in result.messages: content = message.content if isinstance(content, types.TextContent): parts.append(content.text) elif isinstance(content, list): for block in content: if isinstance(block, types.TextContent): parts.append(block.text) else: parts.append(str(block)) else: parts.append(str(content)) return "\n".join(parts) or "(no output)" return "(MCP prompt call failed)" # Unreachable async def connect_mcp_servers( mcp_servers: dict, registry: ToolRegistry ) -> dict[str, AsyncExitStack]: """Connect to configured MCP servers and register their tools, resources, prompts. Returns a dict mapping server name -> its dedicated AsyncExitStack. Each server gets its own stack to prevent cancel scope conflicts when multiple MCP servers are configured. """ from mcp import ClientSession, StdioServerParameters from mcp.client.sse import sse_client from mcp.client.stdio import stdio_client from mcp.client.streamable_http import streamable_http_client async def connect_single_server(name: str, cfg) -> tuple[str, AsyncExitStack | None]: server_stack = AsyncExitStack() await server_stack.__aenter__() try: transport_type = cfg.type if not transport_type: if cfg.command: transport_type = "stdio" elif cfg.url: transport_type = ( "sse" if cfg.url.rstrip("/").endswith("/sse") else "streamableHttp" ) else: logger.warning("MCP server '{}': no command or url configured, skipping", name) await server_stack.aclose() return name, None if transport_type in {"sse", "streamableHttp"}: ok, error = validate_url_target(cfg.url) if not ok: logger.warning( "MCP server '{}': blocked unsafe URL {} ({})", name, _redact_url(cfg.url), error, ) await server_stack.aclose() return name, None if transport_type == "stdio": command, args, env = _normalize_windows_stdio_command( cfg.command, cfg.args, cfg.env or None, ) params = StdioServerParameters( command=command, args=args, env=env, cwd=cfg.cwd or None, ) read, write = await server_stack.enter_async_context(stdio_client(params)) elif transport_type == "sse": if not await _probe_http_url(cfg.url): logger.warning("MCP server '{}': {} unreachable, skipping", name, _redact_url(cfg.url)) await server_stack.aclose() return name, None def httpx_client_factory( headers: dict[str, str] | None = None, timeout: httpx.Timeout | None = None, auth: httpx.Auth | None = None, ) -> httpx.AsyncClient: merged_headers = { "Accept": "application/json, text/event-stream", **(cfg.headers or {}), **(headers or {}), } return httpx.AsyncClient( headers=merged_headers or None, event_hooks={"request": [_validate_mcp_request_url]}, follow_redirects=True, timeout=timeout, auth=auth, ) read, write = await server_stack.enter_async_context( sse_client(cfg.url, httpx_client_factory=httpx_client_factory) ) elif transport_type == "streamableHttp": if not await _probe_http_url(cfg.url): logger.warning("MCP server '{}': {} unreachable, skipping", name, _redact_url(cfg.url)) await server_stack.aclose() return name, None http_client = await server_stack.enter_async_context( httpx.AsyncClient( headers=cfg.headers or None, event_hooks={"request": [_validate_mcp_request_url]}, follow_redirects=True, timeout=httpx.Timeout(30.0, connect=10.0), ) ) read, write, _ = await server_stack.enter_async_context( streamable_http_client(cfg.url, http_client=http_client) ) else: logger.warning("MCP server '{}': unknown transport type '{}'", name, transport_type) await server_stack.aclose() return name, None read = _filter_malformed_mcp_progress_notifications(read, name) session = await server_stack.enter_async_context(ClientSession(read, write)) await session.initialize() tools = await session.list_tools() enabled_tools = set(cfg.enabled_tools) allow_all_tools = "*" in enabled_tools registered_count = 0 matched_enabled_tools: set[str] = set() available_raw_names = [tool_def.name for tool_def in tools.tools] available_wrapped_names = [_sanitize_name(f"mcp_{name}_{tool_def.name}") for tool_def in tools.tools] for tool_def in tools.tools: wrapped_name = _sanitize_name(f"mcp_{name}_{tool_def.name}") if ( not allow_all_tools and tool_def.name not in enabled_tools and wrapped_name not in enabled_tools ): logger.debug( "MCP: skipping tool '{}' from server '{}' (not in enabledTools)", wrapped_name, name, ) continue wrapper = MCPToolWrapper(session, name, tool_def, tool_timeout=cfg.tool_timeout) registry.register(wrapper) logger.debug("MCP: registered tool '{}' from server '{}'", wrapper.name, name) registered_count += 1 if enabled_tools: if tool_def.name in enabled_tools: matched_enabled_tools.add(tool_def.name) if wrapped_name in enabled_tools: matched_enabled_tools.add(wrapped_name) if enabled_tools and not allow_all_tools: unmatched_enabled_tools = sorted(enabled_tools - matched_enabled_tools) if unmatched_enabled_tools: logger.warning( "MCP server '{}': enabledTools entries not found: {}. Available raw names: {}. " "Available wrapped names: {}", name, ", ".join(unmatched_enabled_tools), ", ".join(available_raw_names) or "(none)", ", ".join(available_wrapped_names) or "(none)", ) # Only register resources and prompts when no tool restriction is # active. enabledTools is a per-*tool* allowlist; resources and # prompts have no equivalent name filter, so they must be skipped # whenever the operator specified a tool subset. An empty list # (deny-all) or a list of specific tool names both indicate that # the operator intended to restrict capabilities — registering # unrestricted resource/prompt wrappers would violate that intent. # The default ["*"] (allow-all) means no restriction was intended. register_extras = allow_all_tools if register_extras: try: resources_result = await session.list_resources() for resource in resources_result.resources: wrapper = MCPResourceWrapper( session, name, resource, resource_timeout=cfg.tool_timeout ) registry.register(wrapper) registered_count += 1 logger.debug( "MCP: registered resource '{}' from server '{}'", wrapper.name, name, ) except Exception as e: logger.debug( "MCP server '{}': resources not supported or failed: {}", name, e ) try: prompts_result = await session.list_prompts() for prompt in prompts_result.prompts: wrapper = MCPPromptWrapper( session, name, prompt, prompt_timeout=cfg.tool_timeout ) registry.register(wrapper) registered_count += 1 logger.debug( "MCP: registered prompt '{}' from server '{}'", wrapper.name, name, ) except Exception as e: logger.debug( "MCP server '{}': prompts not supported or failed: {}", name, e ) else: logger.info( "MCP server '{}': skipping resource/prompt registration " "(enabledTools does not include '*' — only tools allowed)", name, ) logger.info( "MCP server '{}': connected, {} capabilities registered", name, registered_count ) return name, server_stack except Exception as e: hint = "" text = str(e).lower() if any( marker in text for marker in ( "parse error", "invalid json", "unexpected token", "jsonrpc", "content-length", ) ): hint = ( " Hint: this looks like stdio protocol pollution. Make sure the MCP server writes " "only JSON-RPC to stdout and sends logs/debug output to stderr instead." ) logger.exception("MCP server '{}': failed to connect: {}", name, hint) with suppress(Exception): await server_stack.aclose() return name, None server_stacks: dict[str, AsyncExitStack] = {} for name, cfg in mcp_servers.items(): try: result = await connect_single_server(name, cfg) except Exception as e: logger.exception("MCP server '{}' connection failed: {}", name, e) continue if result is not None and result[1] is not None: server_stacks[result[0]] = result[1] return server_stacks def session_extra(metadata: Mapping[str, Any] | None) -> dict[str, Any]: """Return persisted session kwargs for MCP preset attachments.""" mcp_presets = metadata.get("mcp_presets") if isinstance(metadata, Mapping) else None return {"mcp_presets": mcp_presets} if isinstance(mcp_presets, list) and mcp_presets else {} def runtime_lines( message: Any, *, available_server_names: set[str] | None = None, configured_server_names: set[str] | None = None, connected_server_names: set[str] | None = None, skip: bool = False, ) -> list[str]: """Return model-visible MCP preset annotations for the current turn.""" if skip: return [] if configured_server_names is None: configured_server_names = available_server_names if connected_server_names is None: connected_server_names = available_server_names metadata = message.metadata if isinstance(getattr(message, "metadata", None), Mapping) else None structured = metadata.get("mcp_presets") if isinstance(metadata, Mapping) else None if not isinstance(structured, list): return [] lines: list[str] = [] for item in structured[:8]: if not isinstance(item, Mapping): continue raw_name = str(item.get("name") or "").strip().lower() if not raw_name: continue display = str(item.get("display_name") or raw_name).strip() or raw_name transport = str(item.get("transport") or "mcp").strip() or "mcp" prefix = f"mcp_{raw_name}_" if configured_server_names is not None and raw_name not in configured_server_names: lines.append( "MCP Preset Attachment: " f"@{raw_name} ({display}; transport={transport}) is configured in WebUI Settings, " "but this gateway has not loaded the latest MCP settings yet. " f"Tools with prefix `{prefix}` may not be available yet; if they are missing, " "tell the user to restart nanobot." ) continue if connected_server_names is not None and raw_name not in connected_server_names: lines.append( "MCP Preset Attachment: " f"@{raw_name} ({display}; transport={transport}) is configured, " "but its MCP connection is not currently live. " f"Tools with prefix `{prefix}` may be unavailable; tell the user to open Settings, " "run the preset test, and restart nanobot only if hot reload is unavailable." ) continue lines.append( "MCP Preset Attachment: " f"@{raw_name} ({display}; transport={transport}; tool_prefix={prefix}). " f"Prefer available tools whose names start with `{prefix}` for this request; " "do not substitute shell commands for this MCP integration unless the user asks." ) return lines async def connect_missing_servers(state: Any, registry: ToolRegistry) -> None: """Connect configured MCP servers that are not currently live.""" missing_servers = { name: cfg for name, cfg in state._mcp_servers.items() if name not in state._mcp_stacks } if state._mcp_connecting or not missing_servers: return state._mcp_connecting = True try: connected = await connect_mcp_servers(missing_servers, registry) state._mcp_stacks.update(connected) _attach_reconnect_handlers(state, registry, connected) state._mcp_connected = bool(state._mcp_stacks) if connected: logger.info("MCP connected servers: {}", sorted(connected)) else: logger.warning("No MCP servers connected successfully (will retry next message)") except asyncio.CancelledError: logger.warning("MCP connection cancelled (will retry next message)") state._mcp_connected = bool(state._mcp_stacks) except BaseException as e: logger.warning("Failed to connect MCP servers (will retry next message): {}", e) state._mcp_connected = bool(state._mcp_stacks) finally: state._mcp_connecting = False async def reload_servers(state: Any, registry: ToolRegistry) -> dict[str, Any]: """Reconcile live MCP connections with the current config file.""" async with _reload_lock(state): try: from nanobot.config.loader import load_config, resolve_config_env_vars config = resolve_config_env_vars(load_config()) next_servers = dict(config.tools.mcp_servers) except Exception as exc: logger.warning("MCP hot reload could not read config: {}", exc) return { "ok": False, "message": "Could not reload MCP config. Restart nanobot to pick up changes.", "requires_restart": True, "error": str(exc), } current_servers = dict(state._mcp_servers) current_names = set(current_servers) next_names = set(next_servers) removed = sorted(current_names - next_names) added = sorted(next_names - current_names) changed = sorted( name for name in current_names & next_names if _server_signature(current_servers[name]) != _server_signature(next_servers[name]) ) tools_removed = 0 for name in [*removed, *changed]: tools_removed += _unregister_server_tools(state, registry, name) await _close_server(state, name) state._mcp_servers = next_servers retry_missing = sorted( name for name in next_names if name not in state._mcp_stacks and name not in set(added) | set(changed) ) to_connect_names = sorted(set(added) | set(changed) | set(retry_missing)) to_connect = {name: next_servers[name] for name in to_connect_names} connected: dict[str, AsyncExitStack] = {} if to_connect: connected = await connect_mcp_servers(to_connect, registry) state._mcp_stacks.update(connected) _attach_reconnect_handlers(state, registry, connected) state._mcp_connected = bool(state._mcp_stacks) failed = sorted(set(to_connect) - set(connected)) unchanged = not removed and not added and not changed and not retry_missing ok = not failed if failed: message = "MCP config reloaded, but some servers did not connect: " + ", ".join(failed) elif unchanged: message = "MCP config is already live." elif retry_missing and not added and not changed and not removed: message = "MCP connections refreshed without restarting nanobot." else: message = "MCP config reloaded without restarting nanobot." logger.info( "MCP hot reload: added={} changed={} removed={} retried={} connected={} failed={} tools_removed={}", added, changed, removed, retry_missing, sorted(connected), failed, tools_removed, ) return { "ok": ok, "message": message, "added": added, "changed": changed, "removed": removed, "retried": retry_missing, "connected": sorted(state._mcp_stacks), "configured": sorted(state._mcp_servers), "failed": failed, "tools_removed": tools_removed, "requires_restart": False, } async def request_mcp_reload(bus: Any, *, timeout: float = 15.0) -> dict[str, Any]: """Ask the running agent loop to reconcile live MCP connections.""" loop = asyncio.get_running_loop() ack: asyncio.Future[dict[str, Any]] = loop.create_future() await bus.publish_inbound( InboundMessage( channel="system", sender_id="webui-settings", chat_id="runtime", content=RUNTIME_CONTROL_MCP_RELOAD, metadata={ INBOUND_META_RUNTIME_CONTROL: RUNTIME_CONTROL_MCP_RELOAD, RUNTIME_CONTROL_ACK: ack, }, ) ) try: result = await asyncio.wait_for(ack, timeout=timeout) except asyncio.TimeoutError: return { "ok": False, "message": "MCP hot reload timed out. Restart nanobot to pick up changes.", "requires_restart": True, } return result if isinstance(result, dict) else { "ok": False, "message": "MCP hot reload returned an unexpected response.", "requires_restart": True, } async def handle_runtime_control(state: Any, msg: InboundMessage, registry: ToolRegistry) -> bool: metadata = msg.metadata if isinstance(msg.metadata, dict) else {} control = metadata.get(INBOUND_META_RUNTIME_CONTROL) if control != RUNTIME_CONTROL_MCP_RELOAD: return False ack = metadata.get(RUNTIME_CONTROL_ACK) try: result = await reload_servers(state, registry) except Exception as exc: logger.exception("MCP hot reload failed") result = { "ok": False, "message": "MCP hot reload failed. Restart nanobot to pick up changes.", "requires_restart": True, "error": str(exc), } if isinstance(ack, asyncio.Future) and not ack.done(): ack.set_result(result) return True def _reload_lock(state: Any) -> asyncio.Lock: try: return _RELOAD_LOCKS[state] except KeyError: lock = asyncio.Lock() _RELOAD_LOCKS[state] = lock return lock def _attach_reconnect_handlers( state: Any, registry: ToolRegistry, server_names: Mapping[str, Any] | set[str] | list[str] | tuple[str, ...], ) -> None: async def reconnect(server_name: str, tool_name: str, stale_tool: Tool) -> Tool | None: return await _refresh_terminated_server( state, registry, server_name, tool_name, stale_tool, ) for server_name in server_names: prefix = _tool_prefix(server_name) for tool_name in list(registry.tool_names): if not tool_name.startswith(prefix): continue tool = registry.get(tool_name) if isinstance(tool, _MCPWrapperBase): tool.set_reconnect_handler(reconnect) async def _refresh_terminated_server( state: Any, registry: ToolRegistry, server_name: str, tool_name: str, stale_tool: Tool, ) -> Tool | None: async with _reload_lock(state): cfg = state._mcp_servers.get(server_name) if cfg is None: logger.warning( "MCP server '{}' session terminated but is no longer configured", server_name, ) return None current_tool = registry.get(tool_name) if ( current_tool is not None and current_tool is not stale_tool and server_name in state._mcp_stacks ): return current_tool logger.warning("MCP server '{}' session terminated; refreshing connection", server_name) _unregister_server_tools(state, registry, server_name) await _close_server(state, server_name) connected = await connect_mcp_servers({server_name: cfg}, registry) state._mcp_stacks.update(connected) _attach_reconnect_handlers(state, registry, connected) state._mcp_connected = bool(state._mcp_stacks) if server_name not in connected: logger.warning("MCP server '{}' reconnect failed after session termination", server_name) return None return registry.get(tool_name) def _server_signature(cfg: Any) -> Any: if hasattr(cfg, "model_dump"): return cfg.model_dump(mode="json") return cfg def _tool_prefix(server_name: str) -> str: return _sanitize_name(f"mcp_{server_name}_") def _unregister_server_tools(state: Any, registry: ToolRegistry, server_name: str) -> int: prefix = _tool_prefix(server_name) removed = 0 for tool_name in list(registry.tool_names): if tool_name.startswith(prefix): registry.unregister(tool_name) removed += 1 return removed async def _close_server(state: Any, server_name: str) -> None: stack = state._mcp_stacks.pop(server_name, None) if stack is None: return try: await stack.aclose() except (RuntimeError, BaseExceptionGroup): logger.debug("MCP server '{}' cleanup error (can be ignored)", server_name)