launchflag-mcp

MCP server for LaunchFlag. It lets a coding agent create a feature flag, ship the risky path dark behind it, and flip it later without a deploy.

Seven tools, one token, no state.

You probably do not need this package. launchflag is the SDK and the CLI, and the hosted MCP server needs nothing installed. launchflag-mcp is only for running that same server locally instead.

Start here

npx launchflag init --key lf_dev_… --token lfk_… --url https://launchflag.dev

From your project root. It installs launchflag, writes the key, downloads the agent skill and points your client at the hosted MCP server.

Hosted, or local

Hosted (the default). Nothing to install. Point your client at https://launchflag.dev/mcp with your API token (lfk_…) in the Authorization header.

Local stdio (the alternative). Runs on your machine and talks to the same API over HTTPS. Useful when your client does not speak Streamable HTTP, or when you self-host LaunchFlag.

npx -y launchflag-mcp@latest

Env vars

| Variable | Required | Default | What it is | | --- | --- | --- | --- | | LAUNCHFLAG_TOKEN | yes | none | Your API token (lfk_…), from the dashboard Install page. The server exits if it is missing. | | LAUNCHFLAG_URL | no | https://launchflag.dev | Base URL of the LaunchFlag instance. Set it only if you self-host. |

The token is a secret. Keep the file that holds it out of git.

The seven tools

| Tool | What it does | | --- | --- | | list_flags | Every flag with its dev, staging and prod state, fail mode and variants. | | create_flag | Creates a flag OFF in all three environments and returns the snippet to wrap the new path in. | | set_flag | Turns a flag on or off, or changes who it targets, in one environment. | | promote_flag | Copies one environment's config forward: dev to staging, or staging to prod. | | delete_flag | Deletes a flag, once the code paths behind it are gone. | | emergency_off | Kill switch: disables every non-essential flag in the project at once, or lifts it. | | list_projects | Your projects and their env keys. |

Claude Code

Hosted:

claude mcp add --transport http launchflag https://launchflag.dev/mcp --header "Authorization: Bearer lfk_…"

Local, in .mcp.json:

{
  "mcpServers": {
    "launchflag": {
      "command": "npx",
      "args": ["-y", "launchflag-mcp@latest"],
      "env": { "LAUNCHFLAG_TOKEN": "lfk_…" }
    }
  }
}

Cursor

.cursor/mcp.json, hosted:

{
  "mcpServers": {
    "launchflag": {
      "type": "http",
      "url": "https://launchflag.dev/mcp",
      "headers": { "Authorization": "Bearer lfk_…" }
    }
  }
}

Swap in the command/args/env block above to run it locally instead.

Codex

codex mcp add has no header flag: it reads a bearer token from an environment variable, which it re-reads every time Codex starts, so put the export in your shell profile.

export LAUNCHFLAG_TOKEN=lfk_…
codex mcp add launchflag --url https://launchflag.dev/mcp --bearer-token-env-var LAUNCHFLAG_TOKEN

Local:

codex mcp add launchflag --env LAUNCHFLAG_TOKEN=lfk_… -- npx -y launchflag-mcp@latest

Docs

Full agent guide, including the skill file and the flag conventions agents should follow: launchflag.dev/docs/agents.

Questions or a bug: [email protected].

MIT licensed.