diff --git a/nanobot/agent/loop.py b/nanobot/agent/loop.py
index dce1890af..f6bd5e2e7 100644
--- a/nanobot/agent/loop.py
+++ b/nanobot/agent/loop.py
@@ -368,7 +368,7 @@ class AgentLoop:
                 WebSearchTool(config=self.web_config.search, proxy=self.web_config.proxy)
             )
             self.tools.register(WebFetchTool(proxy=self.web_config.proxy))
-        self.tools.register(MessageTool(send_callback=self.bus.publish_outbound))
+        self.tools.register(MessageTool(send_callback=self.bus.publish_outbound, workspace=self.workspace))
         self.tools.register(SpawnTool(manager=self.subagents))
         if self.cron_service:
             self.tools.register(
diff --git a/nanobot/agent/tools/message.py b/nanobot/agent/tools/message.py
index f35f8fe23..6e3d037f0 100644
--- a/nanobot/agent/tools/message.py
+++ b/nanobot/agent/tools/message.py
@@ -2,6 +2,7 @@
 
 import os
 from contextvars import ContextVar
+from pathlib import Path
 from typing import Any, Awaitable, Callable
 
 from nanobot.agent.tools.base import Tool, tool_parameters
@@ -35,8 +36,10 @@ class MessageTool(Tool):
         default_channel: str = "",
         default_chat_id: str = "",
         default_message_id: str | None = None,
+        workspace: str | Path | None = None,
     ):
         self._send_callback = send_callback
+        self._workspace = Path(workspace).expanduser() if workspace is not None else get_workspace_path()
         self._default_channel: ContextVar[str] = ContextVar("message_default_channel", default=default_channel)
         self._default_chat_id: ContextVar[str] = ContextVar("message_default_chat_id", default=default_chat_id)
         self._default_message_id: ContextVar[str | None] = ContextVar(
@@ -149,7 +152,7 @@ class MessageTool(Tool):
                 if p.startswith(("http://", "https://")) or os.path.isabs(p):
                     resolved.append(p)
                 else:
-                    resolved.append(str(get_workspace_path() / p))
+                    resolved.append(str(self._workspace / p))
             media = resolved
 
         metadata = dict(self._default_metadata.get()) if same_target else {}
diff --git a/tests/tools/test_message_tool.py b/tests/tools/test_message_tool.py
index d93219f04..915fb0c98 100644
--- a/tests/tools/test_message_tool.py
+++ b/tests/tools/test_message_tool.py
@@ -110,6 +110,26 @@ async def test_message_tool_resolves_relative_media_paths() -> None:
     assert sent[0].media == [expected]
 
 
+@pytest.mark.asyncio
+async def test_message_tool_resolves_relative_media_paths_from_active_workspace(tmp_path) -> None:
+    sent: list[OutboundMessage] = []
+
+    async def _send(msg: OutboundMessage) -> None:
+        sent.append(msg)
+
+    workspace = tmp_path / "workspace"
+    tool = MessageTool(send_callback=_send, workspace=workspace)
+
+    await tool.execute(
+        content="see attached",
+        channel="telegram",
+        chat_id="1",
+        media=["output/image.png"],
+    )
+
+    assert sent[0].media == [str(workspace / "output/image.png")]
+
+
 @pytest.mark.asyncio
 async def test_message_tool_passes_through_absolute_media_paths() -> None:
     sent: list[OutboundMessage] = []