chainlink-feeds-mcp

Instructions

Implementation Reference

• index.js:200-224 (handler)

  The handler function that destructures the 'chain' parameter, validates it using the schema, retrieves the list of feed names from feedsData for that chain, joins them into a comma-separated string, and returns it as text content. Handles errors by returning an error message.

  async ({ chain }) => {
    try {
      // Validate inputs
      const chainKey = chain.toLowerCase();
      listSupportedFeedsByChainSchema.parse({ chain });
  
      // Get feed names as comma-separated string
      const feedNames = feedsData[chainKey].feeds.map((feed) => feed.name).join(',');
  
      return {
        content: [{
          type: 'text',
          text: feedNames
        }]
      };
    } catch (error) {
      return {
        content: [{
          type: 'text',
          text: `Error: ${error.message}`
        }],
        isError: true
      };
    }
  }

• index.js:189-193 (schema)

  Zod schema defining the input parameters for the tool: an object with a required 'chain' string that must correspond to a key in feedsData (validated via refine). Includes description.

  const listSupportedFeedsByChainSchema = z.object({
    chain: z.string().refine((val) => feedsData[val.toLowerCase()], {
      message: 'Unsupported chain'
    }).describe('The blockchain network, e.g., ethereum or base')
  });

• index.js:196-225 (registration)

  Registers the 'listSupportedFeedsByChain' tool with the MCP server via server.tool(), providing the tool name, description, input schema, and inline asynchronous handler function.

  server.tool(
    'listSupportedFeedsByChain',
    'Returns a comma-separated list of price feed names for a specified blockchain network',
    listSupportedFeedsByChainSchema,
    async ({ chain }) => {
      try {
        // Validate inputs
        const chainKey = chain.toLowerCase();
        listSupportedFeedsByChainSchema.parse({ chain });
  
        // Get feed names as comma-separated string
        const feedNames = feedsData[chainKey].feeds.map((feed) => feed.name).join(',');
  
        return {
          content: [{
            type: 'text',
            text: feedNames
          }]
        };
      } catch (error) {
        return {
          content: [{
            type: 'text',
            text: `Error: ${error.message}`
          }],
          isError: true
        };
      }
    }
  );