[Docs] Update MCP authentication from headers to query parameters

Author: joaquim-verges

apps/portal/src/app/ai/mcp/page.mdx

@@ -7,12 +7,7 @@ You can use the thirdweb MCP server to interact with the thirdweb API from your
 You can access the MCP server at the following url, with your project secret key.
 
 ```http
-# endpoint
-POST /mcp
-Host: api.thirdweb.com
-
-# auth header (required)
-x-secret-key <your-project-secret-key>
+POST https://api.thirdweb.com/mcp?secretKey=<your-project-secret-key>
 ```
 
 ### Usage with LLM clients
@@ -27,10 +22,7 @@ Add the following to your `.cursor/mcp.json` file:
 {
   "mcpServers": {
     "thirdweb-api": {
-      "url": "https://api.thirdweb.com/mcp",
-      "headers": {
-        "x-secret-key": "<your-project-secret-key>"
-      }
+      "url": "https://api.thirdweb.com/mcp?secretKey=<your-project-secret-key>",
     }
   }
 }
@@ -50,10 +42,7 @@ client = MultiServerMCPClient(
     {
         "thirdweb-api": {
             "transport": "streamable_http",
-            "url": "https://api.thirdweb.com/mcp",
-            "headers": {
-                "x-secret-key": "<your-project-secret-key>"
-            },
+            "url": "https://api.thirdweb.com/mcp?secretKey=<your-project-secret-key>",
         }
     }
 )