MCP SERVER · OFFICIAL PROJECTReach the whole GrowthBook REST API through two passthrough tools, with bundled skills that spell out the workflow.
LABSCO SUMMARY
Instead of a tool per endpoint, the competence sits in skills — bundled markdown workflows the agent reads before acting, so creating a feature flag follows GrowthBook's documented sequence rather than the model's guess at it. Splitting read from write is what lets a client gate mutations properly, and an expired token comes back as a 401 the client can refresh on rather than as a tool error somebody has to interpret.
A deliberately thin server: an authenticated GET passthrough, an authenticated POST/PUT/PATCH/DELETE passthrough, and two tools that list and read GrowthBook's bundled agent skills — markdown workflows saying which calls a given task needs.
A GrowthBook API key or personal access token in GB_API_KEY. npx @growthbook/mcp runs it over stdio, with GB_API_URL pointing at a self-hosted instance and defaulting to https://api.growthbook.io. For a remote setup, GB_MCP_TRANSPORT=http listens on GB_MCP_PORT 3333 bound to GB_MCP_HOST 127.0.0.1, and GB_MCP_URL is mandatory — the server refuses to start in HTTP mode without it — with OAuth advertised at /.well-known/oauth-protected-resource and OAUTH_AS_ENABLED=1 required on the GrowthBook API side. GB_HTTP_HEADER_* adds extra request headers, for instance for an access proxy in front of the API.
One command plus a key — npx @growthbook/mcp, then supply credentials
USE CASES
List the skills, read the flag-creation workflow, then make exactly the calls it specifies.
Read experiments, features or metrics straight off the REST API by path.
Send the PUT or PATCH the workflow calls for, with the body it lays out.
Point the client at the capability-only path so only the two API tools are advertised.
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
growthbook_api_readMake an authenticated GET request to the GrowthBook REST API. Use path (+ optional query string) exactly as shown in skill workflows that mention gb-call GET. Paths typically start with /api/v1/ or /api/v2/. Returns the raw response body on success. Queries the GrowthBook REST API — see https://docs.growthbook.io/api (OpenAPI: https://api.growthbook.io/api/v1/openapi.yaml).
growthbook_api_writeMake an authenticated mutating request (POST, PUT, PATCH, or DELETE) to the GrowthBook REST API. Use method + path (+ optional JSON body) exactly as shown in skill workflows that mention gb-call with those methods. Paths typically start with /api/v1/ or /api/v2/. Returns the raw response body on success. Mutates the GrowthBook REST API — see https://docs.growthbook.io/api (OpenAPI: https://api.growthbook.io/api/v1/openapi.yaml).
growthbook_list_skillsList available GrowthBook agent skills (name + description). Use growthbook_read_skill to load the full workflow for a skill before acting. Skills encode how to accomplish GrowthBook tasks well; use growthbook_api_read / growthbook_api_write to execute the REST calls they describe.
growthbook_read_skillReturn the full markdown content of a GrowthBook skill by name (from growthbook_list_skills). Follow the skill's workflow; when it shows gb-call <METHOD> <PATH> [body], use growthbook_api_read for GET and growthbook_api_write for POST/PUT/PATCH/DELETE.
BEFORE YOU INSTALL
4 tools when we connected.
CONTEXT COST
Rated by the size of the 4 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Add the block to your client, or run the command directly.
{
"mcpServers": {
"growthbook": {
"command": "npx",
"args": [
"@growthbook/mcp"
],
"env": {
"GB_API_KEY": "<YOUR_GB_API_KEY>",
"GB_API_URL": "https://api.growthbook.io"
}
}
}
}npx @growthbook/mcpMCP servers
configcat
launchdarkly
Unleash