MCP Router

Lets your agent connect to Model Context Protocol servers at runtime, list the tools they expose, invoke one, and disconnect. The factory takes a developer-set allowlist of server configurations; the model can only initiate connections to servers on that list.

The tool exposes five commands: connect (opens a named connection to an allowlisted server using a connection_id), list_connections (returns all open connection IDs for the current agent), list_tools (returns the tools the server exposes), call_tool (invokes a tool by name), and disconnect (closes a connection).

Connections are scoped per agent and persist across invocations on the same agent instance. A connection is closed when the model calls disconnect explicitly, or when the agent is garbage collected. The connection remains open otherwise.

Supported in: Node.js (TypeScript); all platforms (Python).

Security Warning

The allowlist controls which servers the model may connect to. For HTTP servers, treat this like any network request — egress control belongs at the encapsulation layer. For stdio servers, the allowlisted command is spawned as a local process with access to the host filesystem, environment variables, and network. Only allowlist commands you would run directly on the host.

Example:

TypeScript

import { Agent } from '@strands-agents/sdk'
import { makeMcpRouter } from '@strands-agents/sdk/vended-tools/mcp-router'

const mcpRouter = makeMcpRouter({
  servers: {
    files: {
      command: 'npx',
      args: ['-y', '@modelcontextprotocol/server-filesystem', '/tmp'],
    },
    'my-api': { url: 'https://mcp.example.com/mcp' },
  },
  maxConnections: 5,
})
const agent = new Agent({ tools: [mcpRouter] })
await agent.invoke(
  "Connect to 'files', list its tools, " +
    'call the read_file tool on /tmp/hello.txt, then disconnect.'
)

Python

from strands import Agent
from strands.vended_tools import make_mcp_router

mcp_router = make_mcp_router(
    servers={
        "files": {"command": "npx", "args": ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"]},
        "my-api": {"url": "https://mcp.example.com/mcp"},
    },
    max_connections=5,
)
agent = Agent(tools=[mcp_router])
agent(
    "Connect to 'files', list its tools, "
    "call the read_file tool on /tmp/hello.txt, then disconnect."
)

Tags

tool-authoring26