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MCP server

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

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Start the MCP server

handler mcp
The default transport is stdio, which is usually what desktop MCP clients expect.

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Available transports

handler mcp --transport stdio
handler mcp --transport sse
handler mcp --transport streamable-http
Use stdio for local tool integrations and the HTTP-based transports when you need a networked MCP endpoint.

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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.

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Claude Desktop example

Add Handler to claude_desktop_config.json: 
{
  "mcpServers": {
    "handler": {
      "command": "handler",
      "args": ["mcp"]
    }
  }
}

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Typical workflow

One common pattern is:
  1. Save one or more named servers in Handler.
  2. Start handler mcp.
  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.

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When to use this instead of the CLI

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