Cowsay MCP Server

Instructions

Implementation Reference

• src/index.ts:184-204 (handler)

  The main handler function that retrieves the list of available cow characters by running 'cowsay -l' or using the cowsay library API, with fallback list.

  export async function listCows(): Promise<string[]> {
      try {
          const { stdout } = await execAsync(`npx cowsay@1.6.0 -l`);
          return stdout.split('\n').filter(Boolean);
      } catch (error) {
          try {
              const cowsList = await new Promise<string[]>((resolve, reject) => {
                  cowsay.list((error, cow_names) => {
                      if (error) {
                          reject(error);
                      } else {
                          resolve(cow_names || []);
                      }
                  });
              });
              return cowsList;
          } catch (error) {
              return ['default', 'small', 'tux', 'moose', 'sheep', 'dragon', 'elephant', 'skeleton', 'stimpy'];
          }
      }
  }

• src/tools.ts:157-165 (schema)

  Tool schema definition for 'list_cows', specifying no input parameters.

  export const LIST_COWS: Tool = {
    name: 'list_cows',
    title: 'List Cows',
    description: 'List all available cow characters.',
    inputSchema: {
      type: 'object',
      properties: {},
    },
  };

• src/index.ts:107-126 (registration)

  Registers the 'list_cows' tool on the MCP server, providing schema from LIST_COWS and a handler that validates access, calls listCows(), and formats the response as text content.

  mcp_server.registerTool("list_cows", {
      title: LIST_COWS.title,
      description: LIST_COWS.description,
      inputSchema: {},
  }, async () => {
      // Validate server access
      if (!validateServerAccess(config.serverToken)) {
          throw new Error("Server access validation failed. Please provide a valid serverToken.");
      }
      // Apply user preferences from config
      const result = await listCows();
      return {
          content: [
              {
                  type: "text",
                  text: `Available cow characters: ${result.join(', ')}`
              }
          ],
      };
  })