fastmcp-remote 4.0.0a1

A Python stdio bridge for remote MCP servers, powered by FastMCP.

fastmcp-remote

fastmcp-remote is FastMCP's standalone Python stdio bridge for remote MCP servers. It lets MCP clients that launch local stdio processes connect to MCP servers hosted over Streamable HTTP or SSE.

{
  "mcpServers": {
    "linear": {
      "command": "uvx",
      "args": ["fastmcp-remote", "https://mcp.linear.app/mcp"]
    }
  }
}

The CLI is powered by FastMCP. Its command shape is inspired by the original mcp-remote npm project, which established the stdio-to-remote bridge pattern used across the MCP ecosystem.

fastmcp-remote is intentionally smaller than the general FastMCP CLI. It does not load Python files, discover local MCP configs, prepare project environments, or run development reload loops. It builds one FastMCP client for the URL you provide, exposes that client as a local stdio proxy, and leaves the rest alone.

Usage

Run a remote MCP server through a local stdio bridge:

uvx fastmcp-remote https://example.com/mcp

Use the full MCP endpoint URL for the remote server. Many FastMCP HTTP servers expose MCP at /mcp, so a local development server may need http://localhost:8000/mcp rather than http://localhost:8000.

fastmcp-remote starts a local stdio bridge, then connects to the upstream server when the MCP host initializes that bridge. If the upstream server is unavailable, the URL does not point to an MCP endpoint, or authentication cannot complete, initialization fails and the host should report the remote server as failed.

For authenticated MCP servers, OAuth is enabled automatically. To pass a bearer token or other custom header instead, provide a header. The header name ends at the first colon, so values can contain additional colons. Quote the header when the value contains spaces, just like any other shell argument:

uvx fastmcp-remote https://example.com/mcp \
  --header "Authorization: Bearer <token>"

Repeat --header to send multiple headers. Header values use Name: Value format:

uvx fastmcp-remote https://example.com/mcp \
  --header "Authorization: Bearer <token>" \
  --header "X-Workspace: production" \
  --header "X-Client-Name: My MCP Host" \
  --header "X-Callback-Url: https://example.com/oauth/callback"

Some MCP hosts on Windows have trouble preserving spaces inside command arguments. Put the spaced value in an environment variable and reference it from the header value:

{
  "mcpServers": {
    "remote-api": {
      "command": "uvx",
      "args": [
        "fastmcp-remote",
        "https://example.com/mcp",
        "--header",
        "Authorization:${AUTH_HEADER}"
      ],
      "env": {
        "AUTH_HEADER": "Bearer <token>"
      }
    }
  }
}

Use --auth none for unauthenticated development servers:

uvx fastmcp-remote http://localhost:8000/mcp --auth none

For servers behind a self-signed certificate, point --verify at a CA bundle that trusts the certificate:

uvx fastmcp-remote https://internal.example.com/mcp --verify /path/to/ca-bundle.pem

To disable certificate verification entirely (insecure, only for trusted private networks), pass --verify false:

uvx fastmcp-remote https://internal.example.com/mcp --verify false

A CA bundle can also be supplied through the standard SSL_CERT_FILE environment variable, which OpenSSL reads automatically:

SSL_CERT_FILE=/path/to/ca-bundle.pem uvx fastmcp-remote https://internal.example.com/mcp

Options

• --transport: Choose http or sse. Defaults to http.
• --header: Add a header to upstream requests, for example --header "Authorization: Bearer <token>". Values may contain colons. Quote headers whose values contain spaces. Use ${VAR} to expand environment variables inside values. Repeat for multiple headers.
• --resource: Isolate OAuth token storage for a named remote resource.
• --host: Set the OAuth callback hostname. Defaults to localhost.
• --auth-timeout: Set how long to wait for the OAuth callback. Defaults to 300 seconds.
• --ignore-tool: Hide tools whose names match a glob pattern.
• --auth: Choose oauth or none. The default uses OAuth unless an Authorization header is provided.
• --verify: Control TLS certificate verification. Pass a path to a CA bundle to trust a self-signed certificate, or false to disable verification (insecure). Defaults to verification enabled.

OAuth tokens are stored under ~/.fastmcp/remote by default. Set FASTMCP_REMOTE_CONFIG_DIR to use another directory.