Merge PR #554: add MCP support

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: **3,536 lines** (run `bash core_agent_lines.sh` to verify anytime)
+📏 Real-time line count: **3,656 lines** (run `bash core_agent_lines.sh` to verify anytime)
 
 ## 📢 News
 
@@ -683,6 +683,40 @@ That's it! Environment variables, model prefixing, config matching, and `nanobot
 </details>
 
 
+### MCP (Model Context Protocol)
+
+> [!TIP]
+> The config format is compatible with Claude Desktop / Cursor. You can copy MCP server configs directly from any MCP server's README.
+
+nanobot supports [MCP](https://modelcontextprotocol.io/) — connect external tool servers and use them as native agent tools.
+
+Add MCP servers to your `config.json`:
+
+```json
+{
+  "tools": {
+    "mcpServers": {
+      "filesystem": {
+        "command": "npx",
+        "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/dir"]
+      }
+    }
+  }
+}
+```
+
+Two transport modes are supported:
+
+| Mode | Config | Example |
+|------|--------|---------|
+| **Stdio** | `command` + `args` | Local process via `npx` / `uvx` |
+| **HTTP** | `url` | Remote endpoint (`https://mcp.example.com/sse`) |
+
+MCP tools are automatically discovered and registered on startup. The LLM can use them alongside built-in tools — no extra configuration needed.
+
+
+
+
 ### Security
 
 > For production deployments, set `"restrictToWorkspace": true` in your config to sandbox the agent.

nanobot/agent/loop.py

@@ -1,6 +1,7 @@
 """Agent loop: the core processing engine."""
 
 import asyncio
+from contextlib import AsyncExitStack
 import json
 from pathlib import Path
 from typing import Any
@@ -50,6 +51,7 @@ class AgentLoop:
         cron_service: "CronService | None" = None,
         restrict_to_workspace: bool = False,
         session_manager: SessionManager | None = None,
+        mcp_servers: dict | None = None,
     ):
         from nanobot.config.schema import ExecToolConfig
         from nanobot.cron.service import CronService
@@ -82,6 +84,9 @@ class AgentLoop:
         )
         
         self._running = False
+        self._mcp_servers = mcp_servers or {}
+        self._mcp_stack: AsyncExitStack | None = None
+        self._mcp_connected = False
         self._register_default_tools()
     
     def _register_default_tools(self) -> None:
@@ -116,6 +121,16 @@ class AgentLoop:
         if self.cron_service:
             self.tools.register(CronTool(self.cron_service))
     
+    async def _connect_mcp(self) -> None:
+        """Connect to configured MCP servers (one-time, lazy)."""
+        if self._mcp_connected or not self._mcp_servers:
+            return
+        self._mcp_connected = True
+        from nanobot.agent.tools.mcp import connect_mcp_servers
+        self._mcp_stack = AsyncExitStack()
+        await self._mcp_stack.__aenter__()
+        await connect_mcp_servers(self._mcp_servers, self.tools, self._mcp_stack)
+
     def _set_tool_context(self, channel: str, chat_id: str) -> None:
         """Update context for all tools that need routing info."""
         if message_tool := self.tools.get("message"):
@@ -191,6 +206,7 @@ class AgentLoop:
     async def run(self) -> None:
         """Run the agent loop, processing messages from the bus."""
         self._running = True
+        await self._connect_mcp()
         logger.info("Agent loop started")
 
         while self._running:
@@ -213,6 +229,15 @@ class AgentLoop:
             except asyncio.TimeoutError:
                 continue
     
+    async def close_mcp(self) -> None:
+        """Close MCP connections."""
+        if self._mcp_stack:
+            try:
+                await self._mcp_stack.aclose()
+            except (RuntimeError, BaseExceptionGroup):
+                pass  # MCP SDK cancel scope cleanup is noisy but harmless
+            self._mcp_stack = None
+
     def stop(self) -> None:
         """Stop the agent loop."""
         self._running = False
@@ -432,6 +457,7 @@ Respond with ONLY valid JSON, no markdown fences."""
         Returns:
             The agent's response.
         """
+        await self._connect_mcp()
         msg = InboundMessage(
             channel=channel,
             sender_id="user",

nanobot/agent/tools/mcp.py

@@ -0,0 +1,80 @@
+"""MCP client: connects to MCP servers and wraps their tools as native nanobot tools."""
+
+from contextlib import AsyncExitStack
+from typing import Any
+
+from loguru import logger
+
+from nanobot.agent.tools.base import Tool
+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):
+        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": {}}
+
+    @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:
+        from mcp import types
+        result = await self._session.call_tool(self._original_name, arguments=kwargs)
+        parts = []
+        for block in result.content:
+            if isinstance(block, types.TextContent):
+                parts.append(block.text)
+            else:
+                parts.append(str(block))
+        return "\n".join(parts) or "(no output)"
+
+
+async def connect_mcp_servers(
+    mcp_servers: dict, registry: ToolRegistry, stack: AsyncExitStack
+) -> None:
+    """Connect to configured MCP servers and register their tools."""
+    from mcp import ClientSession, StdioServerParameters
+    from mcp.client.stdio import stdio_client
+
+    for name, cfg in mcp_servers.items():
+        try:
+            if cfg.command:
+                params = StdioServerParameters(
+                    command=cfg.command, args=cfg.args, env=cfg.env or None
+                )
+                read, write = await stack.enter_async_context(stdio_client(params))
+            elif cfg.url:
+                from mcp.client.streamable_http import streamable_http_client
+                read, write, _ = await stack.enter_async_context(
+                    streamable_http_client(cfg.url)
+                )
+            else:
+                logger.warning(f"MCP server '{name}': no command or url configured, skipping")
+                continue
+
+            session = await stack.enter_async_context(ClientSession(read, write))
+            await session.initialize()
+
+            tools = await session.list_tools()
+            for tool_def in tools.tools:
+                wrapper = MCPToolWrapper(session, name, tool_def)
+                registry.register(wrapper)
+                logger.debug(f"MCP: registered tool '{wrapper.name}' from server '{name}'")
+
+            logger.info(f"MCP server '{name}': connected, {len(tools.tools)} tools registered")
+        except Exception as e:
+            logger.error(f"MCP server '{name}': failed to connect: {e}")

nanobot/cli/commands.py

@@ -346,6 +346,7 @@ def gateway(
         cron_service=cron,
         restrict_to_workspace=config.tools.restrict_to_workspace,
         session_manager=session_manager,
+        mcp_servers=config.tools.mcp_servers,
     )
     
     # Set cron callback (needs agent)
@@ -403,6 +404,8 @@ def gateway(
             )
         except KeyboardInterrupt:
             console.print("\nShutting down...")
+        finally:
+            await agent.close_mcp()
             heartbeat.stop()
             cron.stop()
             agent.stop()
@@ -453,6 +456,7 @@ def agent(
         brave_api_key=config.tools.web.search.api_key or None,
         exec_config=config.tools.exec,
         restrict_to_workspace=config.tools.restrict_to_workspace,
+        mcp_servers=config.tools.mcp_servers,
     )
     
     # Show spinner when logs are off (no output to miss); skip when logs are on
@@ -469,6 +473,7 @@ def agent(
             with _thinking_ctx():
                 response = await agent_loop.process_direct(message, session_id)
             _print_agent_response(response, render_markdown=markdown)
+            await agent_loop.close_mcp()
         
         asyncio.run(run_once())
     else:
@@ -484,6 +489,7 @@ def agent(
         signal.signal(signal.SIGINT, _exit_on_sigint)
         
         async def run_interactive():
+            try:
                 while True:
                     try:
                         _flush_pending_tty_input()
@@ -508,6 +514,8 @@ def agent(
                         _restore_terminal()
                         console.print("\nGoodbye!")
                         break
+            finally:
+                await agent_loop.close_mcp()
         
         asyncio.run(run_interactive())
 

nanobot/config/schema.py

@@ -216,11 +216,20 @@ class ExecToolConfig(BaseModel):
     timeout: int = 60
 
 
+class MCPServerConfig(BaseModel):
+    """MCP server connection configuration (stdio or HTTP)."""
+    command: str = ""  # Stdio: command to run (e.g. "npx")
+    args: list[str] = Field(default_factory=list)  # Stdio: command arguments
+    env: dict[str, str] = Field(default_factory=dict)  # Stdio: extra env vars
+    url: str = ""  # HTTP: streamable HTTP endpoint URL
+
+
 class ToolsConfig(BaseModel):
     """Tools configuration."""
     web: WebToolsConfig = Field(default_factory=WebToolsConfig)
     exec: ExecToolConfig = Field(default_factory=ExecToolConfig)
     restrict_to_workspace: bool = False  # If true, restrict all tool access to workspace directory
+    mcp_servers: dict[str, MCPServerConfig] = Field(default_factory=dict)
 
 
 class Config(BaseSettings):

pyproject.toml

@@ -38,6 +38,7 @@ dependencies = [
     "qq-botpy>=1.0.0",
     "python-socks[asyncio]>=2.4.0",
     "prompt-toolkit>=3.0.0",
+    "mcp>=1.0.0",
 ]
 
 [project.optional-dependencies]