Fitbit MCP Server

Instructions

Implementation Reference

• src/nutrition.ts:284-332 (handler)

  The core handler function for the 'get_nutrition_by_date_range' tool. It constructs the Fitbit API endpoint for the specified nutrition resource and date range, fetches the data using makeFitbitRequest, handles errors and empty results, and returns the raw JSON response.

  async ({
    resource,
    startDate,
    endDate,
  }: NutritionRangeParams): Promise<ToolResponseStructure> => {
    // Construct the endpoint dynamically
    const endpoint = `foods/log/${resource}/date/${startDate}/${endDate}.json`;
  
    // Make the request
    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 '${resource}' and the date range '${startDate}' to '${endDate}'. Check token, permissions, date format, and ensure the range is 1,095 days or less.`,
          },
        ],
        isError: true,
      };
    }
  
    // Handle no data found
    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}' and the date range '${startDate}' to '${endDate}'.`,
          },
        ],
      };
    }
  
    // Return successful response
    const rawJsonResponse = JSON.stringify(nutritionData, null, 2);
    return {
      content: [{ type: 'text', text: rawJsonResponse }],
    };
  }

• src/nutrition.ts:241-265 (schema)

  Zod input schema for the tool parameters: resource (enum of nutrition types), startDate and endDate (YYYY-MM-DD format strings).

  const rangeParametersSchemaShape = {
    resource: z
      .enum([
        'caloriesIn',
        'water',
        'protein',
        'carbs',
        'fat',
        'fiber',
        'sodium',
      ])
      .describe('The nutrition resource to retrieve data for.'),
    startDate: z
      .string()
      .regex(/^\d{4}-\d{2}-\d{2}$/, 'Start date must be in YYYY-MM-DD format.')
      .describe(
        'The start date for which to retrieve nutrition data (YYYY-MM-DD).'
      ),
    endDate: z
      .string()
      .regex(/^\d{4}-\d{2}-\d{2}$/, 'End date must be in YYYY-MM-DD format.')
      .describe(
        'The end date for which to retrieve nutrition data (YYYY-MM-DD).'
      ),
  };

• src/nutrition.ts:280-333 (registration)

  The server.tool registration call for 'get_nutrition_by_date_range', including name, description, schema reference, and inline handler function. This occurs within the registerNutritionTools function.

  server.tool(
    rangeToolName,
    rangeDescription,
    rangeParametersSchemaShape,
    async ({
      resource,
      startDate,
      endDate,
    }: NutritionRangeParams): Promise<ToolResponseStructure> => {
      // Construct the endpoint dynamically
      const endpoint = `foods/log/${resource}/date/${startDate}/${endDate}.json`;
  
      // Make the request
      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 '${resource}' and the date range '${startDate}' to '${endDate}'. Check token, permissions, date format, and ensure the range is 1,095 days or less.`,
            },
          ],
          isError: true,
        };
      }
  
      // Handle no data found
      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}' and the date range '${startDate}' to '${endDate}'.`,
            },
          ],
        };
      }
  
      // Return successful response
      const rawJsonResponse = JSON.stringify(nutritionData, null, 2);
      return {
        content: [{ type: 'text', text: rawJsonResponse }],
      };
    }
  );

• src/index.ts:82-82 (registration)

  Invocation of registerNutritionTools in the main index.ts, which registers the nutrition tools including get_nutrition_by_date_range.

  registerNutritionTools(server, getAccessToken);

• src/nutrition.ts:267-278 (schema)

  TypeScript type definition for the NutritionRangeParams used in the tool handler and schema.

  type NutritionRangeParams = {
    resource:
      | 'caloriesIn'
      | 'water'
      | 'protein'
      | 'carbs'
      | 'fat'
      | 'fiber'
      | 'sodium';
    startDate: string;
    endDate: string;
  };