console errors if user runs stdio with no api key + gemini key validation in config

Author: Kylejeong2

src/config.ts

@@ -51,6 +51,11 @@ export async function resolveConfig(cliOptions: CLIOptions): Promise<Config> {
   if (!mergedConfig.browserbaseProjectId) {
     mergedConfig.browserbaseProjectId = process.env.BROWSERBASE_PROJECT_ID;
   }
+
+  if (!mergedConfig.modelApiKey) {
+    mergedConfig.modelApiKey = process.env.GEMINI_API_KEY;
+  }
+
   // --------------------------------
 
   // Basic validation for Browserbase keys
@@ -62,6 +67,9 @@ export async function resolveConfig(cliOptions: CLIOptions): Promise<Config> {
       "Warning: BROWSERBASE_PROJECT_ID environment variable not set.",
     );
   }
+  if (!mergedConfig.modelApiKey) {
+    console.warn("Warning: GEMINI_API_KEY environment variable not set.");
+  }
 
   return mergedConfig;
 }

src/program.ts

@@ -79,7 +79,7 @@ program
 
     if (options.port)
       startHttpTransport(+options.port, options.host, serverList);
-    else await startStdioTransport(serverList);
+    else await startStdioTransport(serverList, config);
   });
 
 function setupExitWatchdog(serverList: ServerList) {

src/transport.ts

@@ -6,8 +6,72 @@ import { ServerList } from "./server.js";
 import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
 import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
 import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
+import type { Config } from "../config.js";
+
+export async function startStdioTransport(
+  serverList: ServerList,
+  config?: Config,
+) {
+  // Check if we're using the default model without an API key
+  if (config) {
+    const modelName = config.modelName || "google/gemini-2.0-flash";
+    const hasModelApiKey = config.modelApiKey || process.env.GEMINI_API_KEY;
+
+    if (modelName.includes("google/gemini") && !hasModelApiKey) {
+      console.error(`
+⚠️  IMPORTANT: MCP Server Configuration Update Required
+
+We've made changes to the MCP server that now require model API keys for local STDIO usage.
+
+You're using the default Gemini model (${modelName}) but no API key is configured.
+
+To fix this, you have two options:
+
+1. Set the GEMINI_API_KEY environment variable:
+   export GEMINI_API_KEY="your-gemini-api-key"
+
+2. Or add the --modelApiKey flag to your MCP config:
+   {
+     "mcpServers": {
+       "browserbase": {
+         "command": "npx",
+         "args": ["@browserbasehq/mcp"],
+         "env": {
+           "BROWSERBASE_API_KEY": "your-browserbase-key",
+           "BROWSERBASE_PROJECT_ID": "your-project-id"
+           "GEMINI_API_KEY": "your-gemini-api-key"
+         }
+       }
+     }
+   }
+
+You can get a Gemini API key from: https://aistudio.google.com/app/apikey
+
+3. Or choose another supported model:
+   Available models: https://docs.stagehand.dev/examples/custom_llms#llm-customization
+
+   {
+     "mcpServers": {
+       "browserbase": {
+         "command": "npx",
+         "args": [
+          "@browserbasehq/mcp",
+          "--modelName", "available-model",
+          "--modelApiKey", "your-api-key",
+         ],
+         "env": {
+           "BROWSERBASE_API_KEY": "your-browserbase-key",
+           "BROWSERBASE_PROJECT_ID": "your-project-id"
+         }
+       }
+     }
+   }
+
+The server will now attempt to start, but will likely fail without the API key...
+`);
+    }
+  }
 
-export async function startStdioTransport(serverList: ServerList) {
   const server = await serverList.create();
   await server.connect(new StdioServerTransport());
 }