Fastly MCP Server

The Fastly MCP server lets MCP clients work with the Fastly API.

Connect it to an assistant such as Claude Desktop, Claude Code, Gemini CLI, Opencode, Qwen Code, Cline, or Swival, give it a Fastly API token, and the assistant can look up services, inspect domains and TLS settings, check traffic and usage, manage dictionaries and ACLs, purge content, and make configuration changes when you ask it to.

This project is actively developed and has Tier 1 Fastly open-source support. The support policy is described in Fastly's open-source documentation.

Questions and feedback are welcome on the Fastly developer tools community forum.

How it works

Most MCP servers expose one tool for each operation. Fastly's API is large, so this server uses a smaller workflow that is easier for an assistant to use correctly.

The search tool finds relevant API methods by keyword, method name, API class, or HTTP path. The inspect tool returns the documentation for one method, including parameters, return type, and example usage. The execute tool runs a short JavaScript snippet with the Fastly client already available and authenticated from your environment.

In practice, the assistant should search for the right method, inspect it, and then execute a small call. That keeps the MCP tool list compact while still covering every method documented in the bundled Fastly client docs.

Requirements

The examples below use Bun and its bunx command, which can download and run the package without a global install. You can also run the server with Node.js 22 or newer if you install the package another way.

You also need a Fastly API token. For everyday use, create the narrowest token that fits the work you expect the assistant to do. A read-only token is a good starting point for investigation and reporting. Use a token with write access only when you actually want the assistant to make changes.

Keep the token in your MCP client configuration or shell environment as FASTLY_API_TOKEN. Do not paste production tokens into prompts or commit them into a repository.

Installation

Most MCP clients accept a JSON block that describes how to start a server. This configuration runs the Fastly MCP server with bunx and passes the API token through the environment:

{
  "mcpServers": {
    "fastly": {
      "command": "bunx",
      "args": ["@fastly/mcp"],
      "env": {
        "FASTLY_API_TOKEN": "your-token-here"
      }
    }
  }
}

If you already export FASTLY_API_TOKEN in the shell that starts your MCP client, you can generally omit the env block (some agents may still require it, though).

Keeping the token in the client configuration is often simpler for desktop apps, while shell environment variables are often cleaner for terminal tools.

Claude Code

Run the server through bunx:

claude mcp add fastly -- bunx @fastly/mcp

Then make sure FASTLY_API_TOKEN is available in the environment where Claude Code starts, or configure the token through your normal Claude Code MCP settings.

Claude Desktop

Add the generic JSON block above to Claude Desktop's configuration file. On macOS the file is usually ~/Library/Application Support/Claude/claude_desktop_config.json. On Windows it is usually %APPDATA%\Claude\claude_desktop_config.json. On Linux it is usually ~/.config/Claude/claude_desktop_config.json.

Restart Claude Desktop after changing the file.

Gemini CLI

Add the generic JSON block to ~/.gemini/settings.json. If Gemini CLI is started from a shell that already exports FASTLY_API_TOKEN, you can leave the token out of the JSON.

Opencode

Opencode uses a slightly different shape. Put this in opencode.json in your project, or in ~/.config/opencode/opencode.json for a global server:

{
  "mcp": {
    "fastly": {
      "type": "local",
      "command": ["bunx", "@fastly/mcp"],
      "environment": {
        "FASTLY_API_TOKEN": "your-token-here"
      }
    }
  }
}

Qwen Code

Add the generic JSON block to ~/.qwen/settings.json, or to .qwen/settings.json in a specific project.

Cline

Open Cline MCP settings, choose the global or project MCP configuration, and paste the generic JSON block.

Swival

Add this to swival.toml in your project:

[mcp_servers.fastly]
command = "bunx"
args = ["@fastly/mcp"]
env = { FASTLY_API_TOKEN = "your-token-here" }

If FASTLY_API_TOKEN is already set in the environment where Swival runs, the env line is optional. Swival can also read the generic JSON block from .swival/mcp.json.

Running over HTTP

By default the server speaks MCP over stdio, which is what every desktop and CLI client expects. If instead you want one long-lived server that several clients on the same machine can share — or you want to put the server behind a reverse proxy and reach it remotely — start it with the Streamable HTTP transport:

bunx @fastly/mcp --transport http

That listens on http://127.0.0.1:8231/mcp. Loopback-only by default, no auth, SSE responses. An MCP client that accepts a streamable-http URL can be configured like this:

{
  "mcpServers": {
    "fastly": {
      "type": "streamable-http",
      "url": "http://127.0.0.1:8231/mcp"
    }
  }
}

The exact shape varies by client; check your client's documentation for the streamable-http entry format.

Security notes

A few defaults are deliberately conservative:

• The server binds to 127.0.0.1 unless you say otherwise. Any non-loopback bind (a specific LAN address, 0.0.0.0, or --http-allow-network) refuses to start without an auth token.
• Set the auth token through FASTLY_MCP_HTTP_AUTH_TOKEN rather than --http-auth-token. The CLI flag works, but it lands in shell history and shows up in ps. With the token set, every request except OPTIONS preflights and GET /healthz must carry Authorization: Bearer <token>.
• Requests with an Origin header that is not on the allowlist (set with --http-allow-origin, repeatable, or FASTLY_MCP_HTTP_ALLOW_ORIGIN as a comma-separated list) get 403. Browser-based clients have to opt in. Native clients and curl do not send Origin and pass through.
• The Host header is also validated. Off-loopback binds will reject requests whose Host does not match the bound interface, which is a small but useful guard against DNS rebinding.
• There is no built-in TLS. Run the server behind a reverse proxy (or an ssh tunnel) when you want HTTPS.

Stateful vs stateless

The default mode is stateful: the first request initializes a session, the response carries an Mcp-Session-Id header, and the client sends that header back on every subsequent request. When the client is done it sends DELETE /mcp with the same header and the server tears the session down (204 No Content).

Stateless mode (--http-stateless) builds a fresh MCP server for every request and closes it when the response ends. There are no session IDs, no GET SSE stream, and no DELETE. It is the right choice behind a load balancer or for short-lived clients that do not want to manage session state. Stateless mode implies single-shot JSON responses; pass --http-sse alongside it if you really want SSE framing.

Authorization: Bearer on the loopback

You can set FASTLY_MCP_HTTP_AUTH_TOKEN even on a loopback bind. There is no security harm in doing so, and it makes the configuration portable to a non-loopback deploy later.

Run --help for the full flag list

Every flag described above shows up in bunx @fastly/mcp --help.

Using the server well

A Fastly API token can expose real production configuration, and write-capable tokens can change it. The server does not guess your intent, so the safest workflow is to be explicit about whether the assistant may change anything.

For read-only work, say that directly. For example, ask the assistant to list services, find the active version for a service, summarize backends, check TLS status, inspect logging endpoints, or report recent traffic without making changes.

For write work, give the assistant a clear boundary. Name the service, domain, version, dictionary, ACL, or backend it should work on. Ask it to show the method it plans to call before executing the change. If the change affects service configuration, it is often better to clone a service version, edit the clone, show you the diff or summary, and activate only after you approve.

Good first prompts look like this:

List my Fastly services and show the active version for each one. Do not make changes.

Find the service serving www.example.com and summarize its domains, backends, and health checks.

Inspect the API method for purging one URL, then show me the exact call you would make before running it.

Clone the active version of service ABC123, add a backend named origin-api, and stop before activation.

If an answer looks too broad, ask the assistant to narrow the result in code before returning it. Large Fastly responses are summarized automatically, but targeted calls are easier to review and less likely to leak irrelevant information.

Secret encryption

Fastly API responses can contain credentials, keys, or other sensitive values. By default, the server returns API output to the MCP client as it came back from Fastly. If you want an additional layer of protection before tool output reaches the model, enable secret encryption.

When encryption is enabled, recognized token formats are replaced with encrypted stand-ins before they are returned to the assistant. The replacements keep the same general shape and stay consistent during the server session, so the assistant can refer to them in later calls. Before code runs through execute, the server decrypts any encrypted values it recognizes.

To enable encryption in an MCP configuration that uses bunx, add --encrypt-secrets after the package name:

{
  "mcpServers": {
    "fastly": {
      "command": "bunx",
      "args": ["@fastly/mcp", "--encrypt-secrets"],
      "env": {
        "FASTLY_API_TOKEN": "your-token-here"
      }
    }
  }
}

You can also enable it with an environment variable:

{
  "mcpServers": {
    "fastly": {
      "command": "bunx",
      "args": ["@fastly/mcp"],
      "env": {
        "FASTLY_API_TOKEN": "your-token-here",
        "FASTLY_MCP_ENCRYPT_SECRETS": "true"
      }
    }
  }
}

By default, the encryption key is generated when the server starts. That is usually fine for one session, but encrypted values from an old session cannot be decrypted after a restart. If you need stable encrypted values across restarts, set FASTLY_MCP_ENCRYPT_KEY to exactly 32 hex characters, which is a 16-byte key. You can also set FASTLY_MCP_ENCRYPT_TWEAK if you want a separate tweak value for domain separation.

Secret encryption is a safety feature, not a complete data classification system. It only encrypts values that match known token patterns. You should still use least-privilege Fastly tokens and avoid asking the assistant to retrieve secrets unless the task requires it.

Troubleshooting

If the server starts but Fastly API calls fail, check that FASTLY_API_TOKEN is set in the environment seen by the MCP server. Search and inspect can work without a token because they use bundled documentation, but real API calls need authentication.

If the assistant cannot find the right method, ask it to use broader search terms such as service, domain, backend, purge, tls, logging, dictionary, acl, vcl, stats, or a fragment of the HTTP path from Fastly's API docs.

If a result is unexpectedly empty, ask the assistant to return the raw API response first. Fastly client methods return values directly, not inside a .result wrapper.

If a response is shortened, ask the assistant to filter, page, or select fields in the JavaScript code it runs. The server summarizes very large arrays and objects so that a single tool call does not flood the conversation.

If an execute call times out, split the work into smaller calls. Tool execution is limited to 30 seconds.

Local development

The server entry point is src/index.js. Bun is the primary development runtime:

bun run src/index.js

The main checks are:

bun test
bun run lint

The API documentation in docs/ is generated from the Fastly JavaScript client and is used to build the search index at startup. Regenerate it with:

bun run update-docs

Security

Please report security issues through Fastly's security issue reporting process, as described in SECURITY.md.

License

MIT. See LICENSE for details.