Shadcn UI MCP Server

Implementation Reference

• src/handlers.ts:122-144 (handler)

  The main execution logic for the 'install-blocks' tool: validates input, retrieves block data, selects installation command based on runtime or defaults to npm, and returns the command.

  export const installBlock = async ({block, runtime}: {block: string, runtime?: string}) => {
      try {
          if (runtime && !validateRuntime(runtime)) {
              return createResponse(`Invalid runtime: ${runtime}. Must be one of: npm, pnpm, yarn, bun`, true);
          }
          const { blockData, error } = await getBlockData(block);
          if (error) return createResponse(error, true);
          if (!blockData) return createResponse("Unexpected error: block data missing", true);
  
          if (!blockData.commands?.[0]) {
              return createResponse(`No installation command found for block '${block}'`, true);
          }
          const commands = blockData.commands[0];
          const selectedRuntime = runtime as PackageManager | undefined;
          const command = selectedRuntime ? commands[selectedRuntime] : commands.npm;
          if (!command) {
              return createResponse(`No installation command found for runtime '${runtime}'`, true);
          }
          return createResponse(command);
      } catch (error) {
          return handleError(error, "Error generating installation command");
      }
  }

• src/index.ts:60-63 (schema)

  Zod schema defining the input parameters for the 'install-blocks' tool: required 'block' string and optional 'runtime' string.

  toolSchema: {
      block: z.string().describe("Name of the block to install"),
      runtime: z.string().describe("User runtime (npm, pnpm, yarn, bun)").optional()
  },

• src/index.ts:54-65 (registration)

  Tool definition and registration entry in toolDefinitions object, used for MCP capabilities and server.tool registration. Includes description, JSON parameters schema, Zod toolSchema, and handler reference.

  "install-blocks": {
      description: "Install a shadcn/ui block",
      parameters: {
          block: { type: "string", description: "Name of the block to install" },
          runtime: { type: "string", description: "User runtime (npm, pnpm, yarn, bun)", optional: true }
      },
      toolSchema: {
          block: z.string().describe("Name of the block to install"),
          runtime: z.string().describe("User runtime (npm, pnpm, yarn, bun)").optional()
      },
      handler: installBlock
  },

• src/handlers.ts:87-100 (helper)

  Supporting helper function used by installBlock to retrieve or fetch block data from cache.

  async function getBlockData(block: string) {
      if (!block) {
          return { error: "Block name is required" };
      }
      let blockData = resourceCache.get(block);
      if (!blockData) {
          await fetchAndCacheBlocks();
          blockData = resourceCache.get(block);
      }
      if (!blockData) {
          return { error: `Block '${block}' not found. Use list-blocks to see available blocks.` };
      }
      return { blockData };
  }