MCP Glucose Server

Instructions

Implementation Reference

• src/index.ts:134-162 (handler)

  MCP tool handler for 'get_glucose_readings': extracts parameters, calls the API client, formats and returns the glucose readings as JSON.

  case 'get_glucose_readings': {
    const readings = await api.getGlucoseReadings({
      userId,
      startDate: args?.startDate as string | undefined,
      endDate: args?.endDate as string | undefined,
      limit: (args?.limit as number) || 1000,
    });
  
    return {
      content: [
        {
          type: 'text',
          text: JSON.stringify(
            {
              count: readings.length,
              readings: readings.map((r) => ({
                value: r.value,
                unit: r.unit,
                date: r.date,
                source: r.source,
              })),
            },
            null,
            2
          ),
        },
      ],
    };
  }

• src/index.ts:30-56 (registration)

  Registration of the 'get_glucose_readings' tool in the MCP tools list, including name, description, and input schema.

  {
    name: 'get_glucose_readings',
    description:
      'Get glucose/blood sugar readings for a user within a date range. Returns glucose values in mg/dL with timestamps and sources.',
    inputSchema: {
      type: 'object',
      properties: {
        userId: {
          type: 'string',
          description: `User identifier. Defaults to ${DEFAULT_USER_ID || 'configured user'} if not specified.`,
        },
        startDate: {
          type: 'string',
          description: 'Start date in ISO 8601 format (e.g., 2025-10-01T00:00:00Z). Optional.',
        },
        endDate: {
          type: 'string',
          description: 'End date in ISO 8601 format (e.g., 2025-10-22T23:59:59Z). Optional.',
        },
        limit: {
          type: 'number',
          description: 'Maximum number of readings to return (default: 1000)',
        },
      },
      required: [],
    },
  },

• src/index.ts:34-56 (schema)

  Input schema definition for the 'get_glucose_readings' tool.

    inputSchema: {
      type: 'object',
      properties: {
        userId: {
          type: 'string',
          description: `User identifier. Defaults to ${DEFAULT_USER_ID || 'configured user'} if not specified.`,
        },
        startDate: {
          type: 'string',
          description: 'Start date in ISO 8601 format (e.g., 2025-10-01T00:00:00Z). Optional.',
        },
        endDate: {
          type: 'string',
          description: 'End date in ISO 8601 format (e.g., 2025-10-22T23:59:59Z). Optional.',
        },
        limit: {
          type: 'number',
          description: 'Maximum number of readings to return (default: 1000)',
        },
      },
      required: [],
    },
  },

• src/api-client.ts:46-69 (helper)

  Helper function in HealthDataAPI class that performs the HTTP request to fetch glucose readings from the backend API.

  async getGlucoseReadings(params: {
    userId: string;
    startDate?: string;
    endDate?: string;
    limit?: number;
  }): Promise<GlucoseReading[]> {
    const queryParams = new URLSearchParams({
      userId: params.userId,
      type: 'BloodGlucose',
    });
  
    if (params.startDate) queryParams.append('startDate', params.startDate);
    if (params.endDate) queryParams.append('endDate', params.endDate);
    if (params.limit) queryParams.append('limit', params.limit.toString());
  
    const response = await this.client.get(`/api/samples?${queryParams}`);
  
    return response.data.samples.map((s: any) => ({
      value: s.value,
      unit: s.unit,
      date: s.start_date,
      source: s.source,
    }));
  }