Skip to main content

​
Expose A2A tools through MCP

Handler can expose A2A protocol operations through an MCP server so other tools can call the same card, message, task, session, and auth operations.

​
Configure your agent harness

Most users do not start handler mcp manually. Instead, add it to your agent’s MCP server configuration so the agent harness launches Handler when it needs the tools.

​
Amp or Pi example

Use the same command shape for Amp, Pi, or any MCP client that supports stdio servers: 
{
  "mcpServers": {
    "handler": {
      "command": "handler",
      "args": ["mcp"]
    }
  }
}

​
Run it manually for debugging

For local debugging, you can start the stdio server yourself: 
handler mcp
The default transport is stdio, which is what most local MCP clients expect.

​
Available transports

Start the MCP server with the default stdio transport: 
handler mcp --transport stdio
Start the MCP server with Server-Sent Events transport: 
handler mcp --transport sse
Start the MCP server with streamable HTTP transport: 
handler mcp --transport streamable-http
Use stdio for local tool integrations and the HTTP-based transports when you need a networked MCP endpoint.

​
What the MCP server exposes

The server provides tools across five areas:
  • card lookup and validation
  • message sending
  • task inspection, cancellation, and push config
  • saved session inspection and cleanup
  • credential storage and removal
That makes it useful as a bridge layer between MCP clients and A2A agents.

​
Typical workflow

One common pattern is:
  1. Configure one or more A2A servers in Handler.
  2. Add handler mcp to your agent harness MCP config.
  3. Connect your MCP client.
  4. Use MCP tools to inspect cards, send messages, and manage tasks against those agents.
If you are still experimenting with URLs or auth, the CLI and TUI are usually the fastest way to stabilize that setup first.

​
When to use this instead of the CLI

Use the MCP server when another tool should drive Handler for you. Use the CLI when you want direct shell control or automation in scripts.