MCP Server RubyGems

Instructions

Implementation Reference

• src/tools/get_gem_reverse_dependencies.ts:7-12 (schema)

  Zod input schema defining the gem_name parameter for the tool.

  const GetGemReverseDependenciesInputSchema = z.object({
    gem_name: z
      .string()
      .min(1)
      .describe('Name of the RubyGem to fetch reverse dependencies for'),
  });

• src/tools/get_gem_reverse_dependencies.ts:15-31 (handler)

  Core handler function that fetches and parses reverse dependencies from the RubyGems API.

  async function getGemReverseDependencies(gemName: string): Promise<string[]> {
    const response = await fetch(
      `https://rubygems.org/api/v1/gems/${gemName}/reverse_dependencies.json`
    );
  
    if (!response.ok) {
      if (response.status === 404) {
        throw new Error(`RubyGem '${gemName}' not found`);
      }
      throw new Error(
        `Failed to fetch reverse dependencies: ${response.statusText}`
      );
    }
  
    const data = await response.json();
    return z.array(z.string()).parse(data);
  }

• src/tools/get_gem_reverse_dependencies.ts:34-61 (registration)

  Exports the McpTool object, registering the tool with its name, description, input schema, and wrapper handler.

  export const getGemReverseDependenciesTool: McpTool = {
    name: 'get_gem_reverse_dependencies',
    description: 'Get gems that depend on a specific RubyGem',
    inputSchema: {
      type: 'object',
      properties: zodToJsonSchema(GetGemReverseDependenciesInputSchema),
    },
    handler: async (args: Record<string, unknown> | undefined) => {
      const { gem_name } = GetGemReverseDependenciesInputSchema.parse(args || {});
  
      try {
        const reverseDependencies = await getGemReverseDependencies(gem_name);
        return {
          content: [
            {
              type: 'text',
              text: JSON.stringify(reverseDependencies, null, 2),
            },
          ],
        };
      } catch (error: unknown) {
        return createErrorResponse(
          error,
          'Failed to fetch gem reverse dependencies'
        );
      }
    },
  };

• src/index.ts:20-27 (registration)

  Includes the getGemReverseDependenciesTool in the list of available tools served by the MCP server.

  const tools: readonly McpTool[] = [
    getRubyGemInfoTool,
    searchRubyGemsTool,
    getGemVersionsTool,
    getGemReverseDependenciesTool,
    getOwnerGemsTool,
    getGemOwnersTool,
  ] as const;