FitBit MCP

Implementation Reference

• src/server.ts:324-376 (handler)

  Handler function that fetches weight and body fat measurements from the Fitbit API for the specified date and optional period, returning JSON-formatted data or an error.

  async ({ date, period }) => {
    try {
      const formattedDate = formatDate(date);
      let endpoint = "";
  
      if (period) {
        endpoint = `/user/-/body/log/weight/date/${formattedDate}/${period}.json`;
      } else {
        endpoint = `/user/-/body/log/weight/date/${formattedDate}.json`;
      }
  
      const weightData = await makeApiRequest(endpoint);
  
      // Also get body fat data
      let fatEndpoint = "";
      if (period) {
        fatEndpoint = `/user/-/body/log/fat/date/${formattedDate}/${period}.json`;
      } else {
        fatEndpoint = `/user/-/body/log/fat/date/${formattedDate}.json`;
      }
  
      const fatData = await makeApiRequest(fatEndpoint);
  
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify(
              {
                date: formattedDate,
                weight: weightData.weight || [],
                fat: fatData.fat || [],
              },
              null,
              2
            ),
          },
        ],
      };
    } catch (error) {
      return {
        content: [
          {
            type: "text",
            text: `Error: ${
              error instanceof Error ? error.message : String(error)
            }`,
          },
        ],
        isError: true,
      };
    }
  }

• src/server.ts:314-323 (schema)

  Zod input schema defining optional 'date' and 'period' parameters for the getBodyMeasurements tool.

  {
    date: z
      .string()
      .optional()
      .describe("Date in YYYY-MM-DD format. If not specified, will use today."),
    period: z
      .string()
      .optional()
      .describe("Period for body data: 1d, 7d, 30d, 1w, 1m"),
  },

• src/server.ts:312-377 (registration)

  Registration of the getBodyMeasurements tool on the MCP server, including name, input schema, and handler function.

  server.tool(
    "getBodyMeasurements",
    {
      date: z
        .string()
        .optional()
        .describe("Date in YYYY-MM-DD format. If not specified, will use today."),
      period: z
        .string()
        .optional()
        .describe("Period for body data: 1d, 7d, 30d, 1w, 1m"),
    },
    async ({ date, period }) => {
      try {
        const formattedDate = formatDate(date);
        let endpoint = "";
  
        if (period) {
          endpoint = `/user/-/body/log/weight/date/${formattedDate}/${period}.json`;
        } else {
          endpoint = `/user/-/body/log/weight/date/${formattedDate}.json`;
        }
  
        const weightData = await makeApiRequest(endpoint);
  
        // Also get body fat data
        let fatEndpoint = "";
        if (period) {
          fatEndpoint = `/user/-/body/log/fat/date/${formattedDate}/${period}.json`;
        } else {
          fatEndpoint = `/user/-/body/log/fat/date/${formattedDate}.json`;
        }
  
        const fatData = await makeApiRequest(fatEndpoint);
  
        return {
          content: [
            {
              type: "text",
              text: JSON.stringify(
                {
                  date: formattedDate,
                  weight: weightData.weight || [],
                  fat: fatData.fat || [],
                },
                null,
                2
              ),
            },
          ],
        };
      } catch (error) {
        return {
          content: [
            {
              type: "text",
              text: `Error: ${
                error instanceof Error ? error.message : String(error)
              }`,
            },
          ],
          isError: true,
        };
      }
    }
  );

• src/server.ts:68-72 (helper)

  Helper function to format or default the date to today in YYYY-MM-DD format, used by getBodyMeasurements.

  function formatDate(date?: string): string {
    if (date) return date;
    const today = new Date();
    return today.toISOString().split("T")[0]; // YYYY-MM-DD
  }

• src/server.ts:44-64 (helper)

  Helper function to make authenticated API requests to Fitbit endpoints, used by the getBodyMeasurements handler.

  async function makeApiRequest(endpoint: string): Promise<any> {
    try {
      const url = `${baseUrl}${endpoint}`;
      const response = await fetch(url, {
        headers: {
          Authorization: `Bearer ${accessToken}`,
          Accept: "application/json",
        },
      });
  
      if (!response.ok) {
        throw new Error(
          `Fitbit API error: ${response.status} ${response.statusText}`
        );
      }
  
      return await response.json();
    } catch (error) {
      console.error(`Error making request to ${endpoint}:`, error);
      throw error;
    }