agentmail-mcp

name	agentmail-mcp
description	Configure or troubleshoot the hosted AgentMail MCP server for Codex, Claude Code, Cursor, or another Streamable HTTP MCP client. Use for installation, OAuth, API-key headers, connection failures, or MCP tool discovery. Do not use when the connection already works and the user just wants to send, check, or manage mail — use the sibling action skills for that.

AgentMail MCP

Prefer the hosted Streamable HTTP server:

https://mcp.agentmail.to/mcp

It avoids a local Node.js process and the slower release cadence of the published local MCP package.

Claude Code, Codex, and Cursor

Use OAuth. Do not put an empty API key in the configuration.

{
  "mcpServers": {
    "agentmail": {
      "type": "http",
      "url": "https://mcp.agentmail.to/mcp"
    }
  }
}

Claude Code can also install it directly:

claude mcp add --transport http agentmail https://mcp.agentmail.to/mcp

Complete the browser sign-in on first connection. Multi-organization OAuth sessions can use the server's organization-selection tools.

Per-client configuration

Add the same type: http server entry to the client's MCP config file:

• Cursor: .cursor/mcp.json
• VS Code: .vscode/mcp.json
• Windsurf: its MCP config file
• Claude Desktop: ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%/Claude/claude_desktop_config.json (Windows)

Auth options

• OAuth — browser-based sign-in, for clients that support remote MCP OAuth. Use the bare URL with no credentials.
• x-api-key header — recommended for clients without OAuth support (see below).
• Authorization: Bearer <am_...> header — an alternative header form some clients require.
• apiKey query param — supported but not recommended; prefer a header so the key doesn't end up in logs or history.

For a Streamable HTTP client that cannot complete OAuth, export AGENTMAIL_API_KEY and send it as a header:

{
  "mcpServers": {
    "agentmail": {
      "type": "http",
      "url": "https://mcp.agentmail.to/mcp",
      "headers": {
        "x-api-key": "${env:AGENTMAIL_API_KEY}"
      }
    }
  }
}

Avoid query-string credentials when header authentication is available.

Tool Discovery

MCP clients get the tool catalog and schemas live from the hosted runtime; do not rely on a copied tool count. The same generated contract is published at https://github.com/agentmail-to/agentmail-mcp/blob/main/mcp-manifest.json — treat the hosted runtime plus that manifest as the authoritative catalog. OAuth sessions can surface extra organization-selection tools beyond the base set.

Stdio Compatibility

For a stdio-only client, use the supported npm or PyPI agentmail-mcp package. Both are thin stdio bridges to the same hosted runtime: they discover tools dynamically and carry no separate AgentMail tool logic of their own.

Verify

1. Restart the client or open a new session after installing the plugin.
2. Inspect MCP status in the client and complete authentication.
3. Call list_inboxes as a read-only smoke test.
4. Confirm that read, write, and destructive tool annotations produce the expected approval behavior.

Troubleshoot

• A 404 usually means the URL is missing /mcp.
• "Invalid API key" or a 401 with API-key auth usually means the key is wrong, revoked, lacks the necessary permissions, or AGENTMAIL_API_KEY was not available to the client process.
• "Unauthorized" or a 401 with OAuth usually means the sign-in is incomplete or the session expired — drop any apiKey query param and let the client complete the browser-based OAuth flow instead.
• Use the full am_ key value and prefer the narrowest suitable organization, pod, or inbox scope.
• For a stdio-only client, see Stdio Compatibility above.