fx by Vercel Labs

fx is a native coding agent and CLI from Vercel Labs, and an MCP client. Add Exa’s hosted MCP server to give it live web search and page reading.

Installing fx, adding the Exa MCP server with /mcp add, and running a live Exa web search

Installation

Install fx

curl -fsSL https://fx.sh/setup.sh | bash

Then sign in with fx login. See the fx docs for provider options.

Add Exa

Start fx by running fx, then add the Exa MCP server from the interactive shell:

/mcp add --transport http exa https://mcp.exa.ai/mcp

fx saves the server to ~/.fx/mcp.json and reloads MCP.

Verify the connection

/mcp list

Configure by hand

fx reads MCP servers only from ~/.fx/mcp.json, so you can also add Exa there directly:

~/.fx/mcp.json

{
  "mcp": {
    "exa": {
      "type": "http",
      "url": "https://mcp.exa.ai/mcp"
    }
  }
}

Run /mcp reload to apply the change without restarting fx. The free plan covers casual use. Add your own Exa API key to lift the rate limits:

~/.fx/mcp.json

{
  "mcp": {
    "exa": {
      "type": "http",
      "url": "https://mcp.exa.ai/mcp",
      "header_env": {
        "x-api-key": "EXA_API_KEY"
      }
    }
  }
}

header_env maps a header name to an environment variable, so the key stays out of the config file.

Tool discovery

fx discovers MCP tools lazily: the server’s tools are not in the model’s context until a turn needs them, so adding Exa costs nothing on turns that don’t search the web.

Exa MCP

Review the available tools, configuration options, and other clients.

Last modified on August 26, 2026

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Additional Resources

fx by Vercel Labs

Installation

Configure by hand

Tool discovery

Exa MCP

​Installation

​Configure by hand

​Tool discovery

Exa MCP

Installation

Configure by hand

Tool discovery