fix(mcp): avoid importing unsupported libraries on non-node environments

Author: stainless-app[bot]

packages/mcp-server/src/code-tool.ts

@@ -7,9 +7,7 @@ import { Endpoint, ContentBlock, Metadata } from './tools/types';
 
 import { Tool } from '@modelcontextprotocol/sdk/types.js';
 
-import { newDenoHTTPWorker } from '@valtown/deno-http-worker';
 import { WorkerInput, WorkerError, WorkerSuccess } from './code-tool-types';
-import { workerPath } from './code-tool-paths.cjs';
 
 /**
  * A tool that runs code against a copy of the SDK.
@@ -20,7 +18,7 @@ import { workerPath } from './code-tool-paths.cjs';
  *
  * @param endpoints - The endpoints to include in the list.
  */
-export function codeTool(): Endpoint {
+export async function codeTool(): Promise<Endpoint> {
   const metadata: Metadata = { resource: 'all', operation: 'write', tags: [] };
   const tool: Tool = {
     name: 'execute',
@@ -29,6 +27,10 @@ export function codeTool(): Endpoint {
     inputSchema: { type: 'object', properties: { code: { type: 'string' } } },
   };
 
+  // Import dynamically to avoid failing at import time in cases where the environment is not well-supported.
+  const { newDenoHTTPWorker } = await import('@valtown/deno-http-worker');
+  const { workerPath } = await import('./code-tool-paths.cjs');
+
   const handler = async (client: Finch, args: unknown) => {
     const baseURLHostname = new URL(client.baseURL).hostname;
     const { code } = args as { code: string };

packages/mcp-server/src/index.ts

@@ -14,7 +14,7 @@ async function main() {
     return;
   }
 
-  const selectedTools = selectToolsOrError(endpoints, options);
+  const selectedTools = await selectToolsOrError(endpoints, options);
 
   console.error(
     `MCP Server starting with ${selectedTools.length} tools:`,
@@ -47,9 +47,9 @@ function parseOptionsOrError() {
   }
 }
 
-function selectToolsOrError(endpoints: Endpoint[], options: McpOptions): Endpoint[] {
+async function selectToolsOrError(endpoints: Endpoint[], options: McpOptions): Promise<Endpoint[]> {
   try {
-    const includedTools = selectTools(endpoints, options);
+    const includedTools = await selectTools(endpoints, options);
     if (includedTools.length === 0) {
       console.error('No tools match the provided filters.');
       process.exit(1);

packages/mcp-server/src/server.ts

@@ -55,7 +55,7 @@ export function initMcpServer(params: {
   let providedEndpoints: Endpoint[] | null = null;
   let endpointMap: Record<string, Endpoint> | null = null;
 
-  const initTools = (implementation?: Implementation) => {
+  const initTools = async (implementation?: Implementation) => {
     if (implementation && (!mcpOptions.client || mcpOptions.client === 'infer')) {
       mcpOptions.client =
         implementation.name.toLowerCase().includes('claude') ? 'claude'
@@ -66,8 +66,8 @@ export function initMcpServer(params: {
         ...mcpOptions.capabilities,
       };
     }
-    providedEndpoints = selectTools(endpoints, mcpOptions);
-    endpointMap = Object.fromEntries(providedEndpoints.map((endpoint) => [endpoint.tool.name, endpoint]));
+    providedEndpoints ??= await selectTools(endpoints, mcpOptions);
+    endpointMap ??= Object.fromEntries(providedEndpoints.map((endpoint) => [endpoint.tool.name, endpoint]));
   };
 
   const client = new Finch({
@@ -82,7 +82,7 @@ export function initMcpServer(params: {
 
   server.setRequestHandler(ListToolsRequestSchema, async () => {
     if (providedEndpoints === null) {
-      initTools(server.getClientVersion());
+      await initTools(server.getClientVersion());
     }
     return {
       tools: providedEndpoints!.map((endpoint) => endpoint.tool),
@@ -91,7 +91,7 @@ export function initMcpServer(params: {
 
   server.setRequestHandler(CallToolRequestSchema, async (request) => {
     if (endpointMap === null) {
-      initTools(server.getClientVersion());
+      await initTools(server.getClientVersion());
     }
     const { name, arguments: args } = request.params;
     const endpoint = endpointMap![name];
@@ -106,7 +106,7 @@ export function initMcpServer(params: {
 /**
  * Selects the tools to include in the MCP Server based on the provided options.
  */
-export function selectTools(endpoints: Endpoint[], options?: McpOptions): Endpoint[] {
+export async function selectTools(endpoints: Endpoint[], options?: McpOptions): Promise<Endpoint[]> {
   const filteredEndpoints = query(options?.filters ?? [], endpoints);
 
   let includedTools = filteredEndpoints;
@@ -121,7 +121,7 @@ export function selectTools(endpoints: Endpoint[], options?: McpOptions): Endpoi
     } else if (options?.includeDynamicTools) {
       includedTools = dynamicTools(endpoints);
     } else if (options?.includeCodeTools) {
-      includedTools = [codeTool()];
+      includedTools = [await codeTool()];
     } else {
       includedTools = endpoints;
     }