Merge PR #950: fix(mcp): add configurable timeout to MCP tool calls

README.md

@@ -16,7 +16,7 @@
 
 ⚡️ Delivers core agent functionality in just **~4,000** lines of code — **99% smaller** than Clawdbot's 430k+ lines.
 
-📏 Real-time line count: **3,806 lines** (run `bash core_agent_lines.sh` to verify anytime)
+📏 Real-time line count: **3,862 lines** (run `bash core_agent_lines.sh` to verify anytime)
 
 ## 📢 News
 
@@ -776,6 +776,21 @@ Two transport modes are supported:
 | **Stdio** | `command` + `args` | Local process via `npx` / `uvx` |
 | **HTTP** | `url` + `headers` (optional) | Remote endpoint (`https://mcp.example.com/sse`) |
 
+Use `toolTimeout` to override the default 30s per-call timeout for slow servers:
+
+```json
+{
+  "tools": {
+    "mcpServers": {
+      "my-slow-server": {
+        "url": "https://example.com/mcp/",
+        "toolTimeout": 120
+      }
+    }
+  }
+}
+```
+
 MCP tools are automatically discovered and registered on startup. The LLM can use them alongside built-in tools — no extra configuration needed.
 
 

nanobot/agent/tools/mcp.py

@@ -1,5 +1,6 @@
 """MCP client: connects to MCP servers and wraps their tools as native nanobot tools."""
 
+import asyncio
 from contextlib import AsyncExitStack
 from typing import Any
 
@@ -13,12 +14,13 @@ from nanobot.agent.tools.registry import ToolRegistry
 class MCPToolWrapper(Tool):
     """Wraps a single MCP server tool as a nanobot Tool."""
 
-    def __init__(self, session, server_name: str, tool_def):
+    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._description = tool_def.description or tool_def.name
         self._parameters = tool_def.inputSchema or {"type": "object", "properties": {}}
+        self._tool_timeout = tool_timeout
 
     @property
     def name(self) -> str:
@@ -34,7 +36,14 @@ class MCPToolWrapper(Tool):
 
     async def execute(self, **kwargs: Any) -> str:
         from mcp import types
-        result = await self._session.call_tool(self._original_name, arguments=kwargs)
+        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)"
         parts = []
         for block in result.content:
             if isinstance(block, types.TextContent):
@@ -83,7 +92,7 @@ async def connect_mcp_servers(
 
             tools = await session.list_tools()
             for tool_def in tools.tools:
-                wrapper = MCPToolWrapper(session, name, tool_def)
+                wrapper = MCPToolWrapper(session, name, tool_def, tool_timeout=cfg.tool_timeout)
                 registry.register(wrapper)
                 logger.debug("MCP: registered tool '{}' from server '{}'", wrapper.name, name)
 

nanobot/config/schema.py

@@ -260,6 +260,7 @@ class MCPServerConfig(Base):
     env: dict[str, str] = Field(default_factory=dict)  # Stdio: extra env vars
     url: str = ""  # HTTP: streamable HTTP endpoint URL
     headers: dict[str, str] = Field(default_factory=dict)  # HTTP: Custom HTTP Headers
+    tool_timeout: int = 30  # Seconds before a tool call is cancelled
 
 
 class ToolsConfig(Base):