Fitbit MCP Server

Instructions

Implementation Reference

• src/nutrition.ts:185-232 (handler)

  The core handler function that executes the 'get_nutrition' tool logic. It constructs the Fitbit API endpoint based on the resource, period, and date parameters, fetches the data using makeFitbitRequest, handles errors and empty responses, and returns the raw JSON data.

  async ({
    resource,
    period,
    date = 'today',
  }: NutritionPeriodParams): Promise<ToolResponseStructure> => {
    // Construct the endpoint dynamically
    const endpoint = `foods/log/${resource}/date/${date}/${period}.json`;
  
    const nutritionData =
      await makeFitbitRequest<NutritionTimeSeriesResponse>(
        endpoint,
        getAccessTokenFn,
        FITBIT_API_BASE
      );
  
    // Handle API call failure
    if (!nutritionData) {
      return {
        content: [
          {
            type: 'text',
            text: `Failed to retrieve nutrition data from Fitbit API for resource '${resource}', date '${date}' and period '${period}'. Check token and permissions.`,
          },
        ],
        isError: true,
      };
    }
  
    // Handle no data found for the period
    const resourceKey = `foods-log-${resource}`;
    const nutritionEntries = nutritionData[resourceKey] || [];
    if (nutritionEntries.length === 0) {
      return {
        content: [
          {
            type: 'text',
            text: `No nutrition data found for resource '${resource}', date '${date}' and period '${period}'.`,
          },
        ],
      };
    }
  
    // Return successful response with raw JSON
    const rawJsonResponse = JSON.stringify(nutritionData, null, 2);
    return {
      content: [{ type: 'text', text: rawJsonResponse }],
    };
  }

• src/nutrition.ts:141-166 (schema)

  Zod schema defining the input parameters for the 'get_nutrition' tool: resource (enum of nutrition types), period (time range enum), and optional date.

  const periodParametersSchemaShape = {
    resource: z
      .enum([
        'caloriesIn',
        'water',
        'protein',
        'carbs',
        'fat',
        'fiber',
        'sodium',
      ])
      .describe('The nutrition resource to retrieve data for.'),
    period: z
      .enum(['1d', '7d', '30d', '1w', '1m', '3m', '6m', '1y'])
      .describe('The time period for which to retrieve nutrition data.'),
    date: z
      .string()
      .regex(
        /^\d{4}-\d{2}-\d{2}$|^today$/,
        "Date must be in YYYY-MM-DD format or 'today'."
      )
      .optional()
      .describe(
        "The date for which to retrieve nutrition data (YYYY-MM-DD or 'today'). Defaults to 'today'."
      ),
  };

• src/nutrition.ts:181-233 (registration)

  Local registration of the 'get_nutrition' tool within the registerNutritionTools function using server.tool() with name 'get_nutrition', description, schema, and inline handler.

  server.tool(
    periodToolName,
    periodDescription,
    periodParametersSchemaShape,
    async ({
      resource,
      period,
      date = 'today',
    }: NutritionPeriodParams): Promise<ToolResponseStructure> => {
      // Construct the endpoint dynamically
      const endpoint = `foods/log/${resource}/date/${date}/${period}.json`;
  
      const nutritionData =
        await makeFitbitRequest<NutritionTimeSeriesResponse>(
          endpoint,
          getAccessTokenFn,
          FITBIT_API_BASE
        );
  
      // Handle API call failure
      if (!nutritionData) {
        return {
          content: [
            {
              type: 'text',
              text: `Failed to retrieve nutrition data from Fitbit API for resource '${resource}', date '${date}' and period '${period}'. Check token and permissions.`,
            },
          ],
          isError: true,
        };
      }
  
      // Handle no data found for the period
      const resourceKey = `foods-log-${resource}`;
      const nutritionEntries = nutritionData[resourceKey] || [];
      if (nutritionEntries.length === 0) {
        return {
          content: [
            {
              type: 'text',
              text: `No nutrition data found for resource '${resource}', date '${date}' and period '${period}'.`,
            },
          ],
        };
      }
  
      // Return successful response with raw JSON
      const rawJsonResponse = JSON.stringify(nutritionData, null, 2);
      return {
        content: [{ type: 'text', text: rawJsonResponse }],
      };
    }
  );

• src/index.ts:82-82 (registration)

  Top-level call to registerNutritionTools in the main server setup, which includes registering the 'get_nutrition' tool.

  registerNutritionTools(server, getAccessToken);