NASA MCP Server

Instructions

Implementation Reference

• src/handlers/jpl/jd_cal.ts:13-60 (handler)

  The core handler function `jdCalHandler` that executes the `jpl_jd_cal` tool. It validates input, transforms parameters, calls the JPL JD Calendar API, adds result as resource, and returns formatted JSON response.

  export async function jdCalHandler(args: Record<string, any>) {
    try {
      // Base URL for the JD Calendar API
      const baseUrl = 'https://ssd-api.jpl.nasa.gov/jd_cal.api';
      
      // Validate parameters
      if (!args.jd && !args.cd) {
        return {
          content: [{
            type: "text",
            text: "Error: Either a Julian date (jd) or calendar date (cd) must be provided."
          }],
          isError: true
        };
      }
      
      // Transform parameter names from underscore to hyphenated format
      const transformedParams = transformParamsToHyphenated(args);
      
      // Make the API request
      const response = await axios.get(baseUrl, { params: transformedParams });
      const data = response.data;
      
      // Add response to resources
      const resourceUri = `jpl://jd_cal/${args.jd || args.cd}`;
      addResource(resourceUri, {
        name: `Julian Date / Calendar Date Conversion: ${args.jd || args.cd}`,
        mimeType: "application/json",
        text: JSON.stringify(data, null, 2)
      });
      
      // Format the response
      return {
        content: [{
          type: "text",
          text: JSON.stringify(data, null, 2)
        }]
      };
    } catch (error: any) {
      return {
        content: [{
          type: "text",
          text: `Error accessing JPL Julian Date Calendar API: ${error.message}`
        }],
        isError: true
      };
    }
  }

• src/index.ts:1071-1086 (schema)

  Input schema definition for the `jpl_jd_cal` tool in the tools/list response, specifying parameters `jd` and `cd`.

    name: "jpl_jd_cal",
    description: "Julian Day number to/from calendar date/time converter",
    inputSchema: {
      type: "object",
      properties: {
        jd: {
          type: "string",
          description: "Julian date to convert to calendar date"
        },
        cd: {
          type: "string",
          description: "Calendar date to convert to Julian date (YYYY-MM-DD or YYYY-MM-DDThh:mm:ss format)"
        }
      }
    }
  },

• src/index.ts:513-516 (registration)

  Registration of the `jpl_jd_cal` tool in the tools/manifest response, providing name, id, and description.

    name: "jpl_jd_cal",
    id: "jpl/jd_cal",
    description: "Julian Day number to/from calendar date/time converter"
  },

• src/index.ts:2110-2116 (registration)

  Global registration of `mcp__jpljd_cal` tool wrapper that delegates to the `jpl/jd_cal` handler.

  registerGlobalTool('mcp__jpljd_cal', async (args: Record<string, any>) => {
    serverInstance?.sendLoggingMessage({
      level: "info",
      data: `MCP JPL JD Calendar called with args: ${JSON.stringify(args)}`,
    });
    return await handleToolCall('jpl/jd_cal', args);
  });