GrowthBook MCP Server

Instructions

Implementation Reference

• src/tools/features.ts:237-268 (handler)

  The handler function that implements the logic for fetching feature flags from the GrowthBook API, supporting pagination (limit, offset) and project filtering.

  async ({ limit, offset, project }) => {
    try {
      const queryParams = new URLSearchParams({
        limit: limit?.toString(),
        offset: offset?.toString(),
      });
  
      if (project) {
        queryParams.append("projectId", project);
      }
  
      const res = await fetch(
        `${baseApiUrl}/api/v1/features?${queryParams.toString()}`,
        {
          headers: {
            Authorization: `Bearer ${apiKey}`,
            "Content-Type": "application/json",
          },
        }
      );
  
      await handleResNotOk(res);
  
      const data = await res.json();
  
      return {
        content: [{ type: "text", text: JSON.stringify(data, null, 2) }],
      };
    } catch (error) {
      throw new Error(`Error fetching flags: ${error}`);
    }
  }

• src/tools/features.ts:227-269 (registration)

  The server.tool call that registers the 'get_feature_flags' tool, specifying its name, description, input schema, read-only hint, and handler function.

  server.tool(
    "get_feature_flags",
    "Fetches all feature flags from the GrowthBook API, with optional limit, offset, and project filtering.",
    {
      project: featureFlagSchema.project.optional(),
      ...paginationSchema,
    },
    {
      readOnlyHint: true,
    },
    async ({ limit, offset, project }) => {
      try {
        const queryParams = new URLSearchParams({
          limit: limit?.toString(),
          offset: offset?.toString(),
        });
  
        if (project) {
          queryParams.append("projectId", project);
        }
  
        const res = await fetch(
          `${baseApiUrl}/api/v1/features?${queryParams.toString()}`,
          {
            headers: {
              Authorization: `Bearer ${apiKey}`,
              "Content-Type": "application/json",
            },
          }
        );
  
        await handleResNotOk(res);
  
        const data = await res.json();
  
        return {
          content: [{ type: "text", text: JSON.stringify(data, null, 2) }],
        };
      } catch (error) {
        throw new Error(`Error fetching flags: ${error}`);
      }
    }
  );

• src/utils.ts:218-238 (schema)

  The paginationSchema defining limit, offset, and mostRecent parameters used in the get_feature_flags tool schema.

  export const paginationSchema = {
    limit: z
      .number()
      .min(1)
      .max(100)
      .default(100)
      .describe("The number of items to fetch (1-100)"),
    offset: z
      .number()
      .min(0)
      .default(0)
      .describe(
        "The number of items to skip. For example, set to 100 to fetch the second page with default limit. Note: The API returns items in chronological order (oldest first) by default."
      ),
    mostRecent: z
      .boolean()
      .default(false)
      .describe(
        "When true, fetches the most recent items and returns them newest-first. When false (default), returns oldest items first."
      ),
  } as const;

• src/utils.ts:254-257 (schema)

  The 'project' field from featureFlagSchema used optionally in the get_feature_flags tool input schema.

  project: z
    .string()
    .describe("The ID of the project to which the feature flag belongs"),
  // Contextual info

• src/index.ts:81-87 (registration)

  High-level registration of feature tools (including get_feature_flags) via registerFeatureTools in the main MCP server setup.

  registerFeatureTools({
    server,
    baseApiUrl,
    apiKey,
    appOrigin,
    user,
  });