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strands.vended_tools.mcp_router.mcp_router

Agent-callable MCP router tool.

Provides :func:make_mcp_router (a factory bound to a developer-set server allowlist).

The tool exposes five commands — connect, list_connections, list_tools, call_tool, disconnect — letting an agent open named connections to MCP servers, inspect active connections, discover their tools, invoke them, and close the connections. Each server is configured with a :class:~strands.tools.mcp.MCPServerConfig; all fields are forwarded to :class:~strands.tools.mcp.MCPClient. Connections are isolated per agent.

MCPRouterToolError

Section titled “MCPRouterToolError”
class MCPRouterToolError(RuntimeError)

Defined in: src/strands/vended_tools/mcp_router/mcp_router.py:36

Raised when an mcp_router tool operation fails.

make_mcp_router

Section titled “make_mcp_router”
def make_mcp_router(
        *,
        name: str = "mcp_router",
        description: str | None = None,
        servers: dict[str, MCPServerConfig],
        max_connections: int = _DEFAULT_MAX_CONNECTIONS
) -> DecoratedFunctionTool

Defined in: src/strands/vended_tools/mcp_router/mcp_router.py:40

Create an agent-callable MCP router tool bound to a developer-set server allowlist.

MCP connections are scoped per agent and persist across invocations. They are closed when the model calls disconnect explicitly or when the agent is garbage collected. Connections remain open otherwise.

Arguments:

  • name - Tool name shown to the model.
  • description - Tool description shown to the model. Defaults to a description that includes the permitted server names.
  • servers - Allowlisted servers keyed by name. The model identifies servers to connect to by name; the config is forwarded to :class:~strands.tools.mcp.MCPClient. Must not be empty.
  • max_connections - Maximum simultaneous open connections per agent. Defaults to 10.

Returns:

A decorated tool that manages MCP connections.

Raises:

  • ValueError - If servers is empty or max_connections is not positive.