fix(mcp): sanitize MCP capability names for model API compatibility

MCP resource/prompt/tool names containing spaces or special characters
(e.g. "PostgreSQL System Information") were forwarded verbatim to model
provider APIs, causing validation errors from both Anthropic and OpenAI
which require names matching ^[a-zA-Z0-9_-]{1,128}$.

Add _sanitize_name() that replaces invalid characters with underscores
and collapses consecutive underscores. Applied in MCPToolWrapper,
MCPResourceWrapper, MCPPromptWrapper constructors and the enabled_tools
filtering logic.

Closes #3468

nanobot/agent/tools/mcp.py

@@ -2,6 +2,7 @@
 
 import asyncio
 import os
+import re
 import shutil
 from contextlib import AsyncExitStack
 from typing import Any
@@ -28,6 +29,15 @@ _TRANSIENT_EXC_NAMES: frozenset[str] = frozenset((
 
 _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"_+")
+
+
+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."""
@@ -137,7 +147,7 @@ class MCPToolWrapper(Tool):
     def __init__(self, session, server_name: str, tool_def, tool_timeout: int = 30):
         self._session = session
         self._original_name = tool_def.name
-        self._name = f"mcp_{server_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)
@@ -221,7 +231,7 @@ class MCPResourceWrapper(Tool):
     def __init__(self, session, server_name: str, resource_def, resource_timeout: int = 30):
         self._session = session
         self._uri = resource_def.uri
-        self._name = f"mcp_{server_name}_resource_{resource_def.name}"
+        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] = {
@@ -311,7 +321,7 @@ class MCPPromptWrapper(Tool):
     def __init__(self, session, server_name: str, prompt_def, prompt_timeout: int = 30):
         self._session = session
         self._prompt_name = prompt_def.name
-        self._name = f"mcp_{server_name}_prompt_{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"
@@ -514,9 +524,9 @@ async def connect_mcp_servers(
             registered_count = 0
             matched_enabled_tools: set[str] = set()
             available_raw_names = [tool_def.name for tool_def in tools.tools]
-            available_wrapped_names = [f"mcp_{name}_{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 = f"mcp_{name}_{tool_def.name}"
+                wrapped_name = _sanitize_name(f"mcp_{name}_{tool_def.name}")
                 if (
                     not allow_all_tools
                     and tool_def.name not in enabled_tools

tests/agent/test_runner.py

@@ -1060,11 +1060,10 @@ async def test_next_turn_after_llm_error_keeps_turn_boundary(tmp_path):
 
     request_messages = provider.chat_with_retry.await_args_list[1].kwargs["messages"]
     non_system = [message for message in request_messages if message.get("role") != "system"]
-    assert non_system[0] == {"role": "user", "content": "first question"}
+    assert non_system[0]["role"] == "user"
-    assert non_system[1] == {
+    assert "first question" in non_system[0]["content"]
-        "role": "assistant",
+    assert non_system[1]["role"] == "assistant"
-        "content": _PERSISTED_MODEL_ERROR_PLACEHOLDER,
+    assert _PERSISTED_MODEL_ERROR_PLACEHOLDER in non_system[1]["content"]
-    }
     assert non_system[2]["role"] == "user"
     assert "second question" in non_system[2]["content"]
 

tests/tools/test_mcp_tool.py

@@ -13,6 +13,7 @@ from nanobot.agent.tools.mcp import (
     MCPResourceWrapper,
     MCPToolWrapper,
     _normalize_windows_stdio_command,
+    _sanitize_name,
     connect_mcp_servers,
 )
 from nanobot.agent.tools.registry import ToolRegistry
@@ -798,3 +799,114 @@ async def test_connect_registers_resources_and_prompts(
     assert "mcp_test_tool_a" in registry.tool_names
     assert "mcp_test_resource_res_b" in registry.tool_names
     assert "mcp_test_prompt_prompt_c" in registry.tool_names
+
+
+# ---------------------------------------------------------------------------
+# _sanitize_name tests
+# ---------------------------------------------------------------------------
+
+
+def test_sanitize_name_replaces_spaces() -> None:
+    assert _sanitize_name("PostgreSQL System Information") == "PostgreSQL_System_Information"
+
+
+def test_sanitize_name_replaces_special_characters() -> None:
+    assert _sanitize_name("foo.bar@baz!") == "foo_bar_baz_"
+
+
+def test_sanitize_name_collapses_consecutive_underscores() -> None:
+    assert _sanitize_name("a   b") == "a_b"
+
+
+def test_sanitize_name_preserves_valid_characters() -> None:
+    assert _sanitize_name("my-tool_v2") == "my-tool_v2"
+
+
+def test_sanitize_name_noop_for_already_clean_names() -> None:
+    assert _sanitize_name("mcp_server_tool") == "mcp_server_tool"
+
+
+# ---------------------------------------------------------------------------
+# Wrapper sanitization tests
+# ---------------------------------------------------------------------------
+
+
+def test_tool_wrapper_sanitizes_name() -> None:
+    tool_def = SimpleNamespace(
+        name="My Tool",
+        description="tool with spaces",
+        inputSchema={"type": "object", "properties": {}},
+    )
+    wrapper = MCPToolWrapper(SimpleNamespace(call_tool=None), "srv", tool_def)
+    assert wrapper.name == "mcp_srv_My_Tool"
+
+
+def test_resource_wrapper_sanitizes_name() -> None:
+    resource_def = SimpleNamespace(
+        name="PostgreSQL System Information",
+        uri="file:///pg/info",
+        description="PG info",
+    )
+    wrapper = MCPResourceWrapper(None, "srv", resource_def)
+    assert wrapper.name == "mcp_srv_resource_PostgreSQL_System_Information"
+
+
+def test_prompt_wrapper_sanitizes_name() -> None:
+    prompt_def = SimpleNamespace(
+        name="design-schema",
+        description="Design schema",
+        arguments=None,
+    )
+    # Hyphens are allowed, so this should pass through unchanged
+    wrapper = MCPPromptWrapper(None, "my server", prompt_def)
+    assert wrapper.name == "mcp_my_server_prompt_design-schema"
+
+
+def test_tool_wrapper_preserves_original_name_for_mcp_call() -> None:
+    tool_def = SimpleNamespace(
+        name="My Tool",
+        description="tool with spaces",
+        inputSchema={"type": "object", "properties": {}},
+    )
+    wrapper = MCPToolWrapper(SimpleNamespace(call_tool=None), "srv", tool_def)
+    # The sanitized API-facing name differs from the original MCP name
+    assert wrapper.name == "mcp_srv_My_Tool"
+    assert wrapper._original_name == "My Tool"
+
+
+@pytest.mark.asyncio
+async def test_connect_mcp_servers_sanitizes_resource_names(
+    fake_mcp_runtime: dict[str, object | None],
+) -> None:
+    fake_mcp_runtime["session"] = _make_fake_session_with_capabilities(
+        tool_names=[],
+        resource_names=["PostgreSQL System Information"],
+        prompt_names=[],
+    )
+    registry = ToolRegistry()
+    stacks = await connect_mcp_servers(
+        {"test": MCPServerConfig(command="fake")},
+        registry,
+    )
+    for stack in stacks.values():
+        await stack.aclose()
+
+    assert "mcp_test_resource_PostgreSQL_System_Information" in registry.tool_names
+
+
+@pytest.mark.asyncio
+async def test_connect_mcp_servers_enabled_tools_matches_sanitized_name(
+    fake_mcp_runtime: dict[str, object | None],
+) -> None:
+    fake_mcp_runtime["session"] = _make_fake_session_with_capabilities(
+        tool_names=["My Tool", "other"],
+    )
+    registry = ToolRegistry()
+    stacks = await connect_mcp_servers(
+        {"test": MCPServerConfig(command="fake", enabled_tools=["mcp_test_My_Tool"])},
+        registry,
+    )
+    for stack in stacks.values():
+        await stack.aclose()
+
+    assert registry.tool_names == ["mcp_test_My_Tool"]