diff --git a/AUTH_SETUP.md b/AUTH_SETUP.md
index 30ab634..c9db9cc 100644
--- a/AUTH_SETUP.md
+++ b/AUTH_SETUP.md
@@ -77,9 +77,12 @@ API key authentication ENABLED (1 key(s) configured)
 # Without key - should fail with 401
 curl https://mcp.yourdomain.com/mcp/tools
 
-# With valid key - should succeed
+# With valid key (header) - should succeed
 curl -H "Authorization: Bearer YOUR_KEY_HERE" \
      https://mcp.yourdomain.com/mcp/tools
+
+# With valid key (query param) - should succeed
+curl "https://mcp.yourdomain.com/mcp/tools?api_key=YOUR_KEY_HERE"
 ```
 
 ---
diff --git a/CHATGPT_SETUP.md b/CHATGPT_SETUP.md
index 412bf16..401658f 100644
--- a/CHATGPT_SETUP.md
+++ b/CHATGPT_SETUP.md
@@ -29,8 +29,7 @@ aegis-gitea-mcp   Up    0.0.0.0:8080->8080/tcp
 
 ```bash
 # Replace YOUR_API_KEY with your actual key
-curl -H "Authorization: Bearer YOUR_API_KEY" \
-     https://mcp.yourdomain.com/mcp/tools
+curl "https://mcp.yourdomain.com/mcp/tools?api_key=YOUR_API_KEY"
 
 # Expected: JSON response with available tools
 # If error: Check AUTH_SETUP.md troubleshooting
@@ -50,22 +49,12 @@ curl -H "Authorization: Bearer YOUR_API_KEY" \
 3. **Enter Server Details**
    ```
    Name:        AegisGitea MCP
-   URL:         https://mcp.yourdomain.com
+   URL:         https://mcp.yourdomain.com?api_key=YOUR_API_KEY_HERE
    Type:        HTTP/SSE (Server-Sent Events)
+   Auth:        None (or Mixed, leave OAuth fields empty)
    ```
 
-4. **Add Custom Header**
-   ```
-   Header Name:  Authorization
-   Header Value: Bearer YOUR_API_KEY_HERE
-   ```
-
-   **Important:**
-   - Include the word "Bearer" followed by a space
-   - Then paste your full 64-character API key
-   - No quotes around the key
-
-5. **Save Configuration**
+4. **Save Configuration**
 
 ### Step 4: Test Connection
 
@@ -168,18 +157,18 @@ curl https://mcp.yourdomain.com/health
 
 ### Issue: "Authentication failed"
 
-**Check 1: Authorization header format**
+**Check 1: MCP Server URL format**
 
 Correct:
 ```
-Authorization: Bearer a1b2c3d4e5f6g7h8...
+https://mcp.yourdomain.com?api_key=YOUR_KEY
 ```
 
 Wrong:
 ```
-Authorization: a1b2c3d4...              (missing "Bearer ")
-Authorization: "Bearer a1b2c3d4..."     (extra quotes)
-Authorization:Bearer a1b2c3d4...        (missing space after colon)
+https://mcp.yourdomain.com                (missing api_key)
+https://mcp.yourdomain.com?api_key=       (empty key)
+https://mcp.yourdomain.com?api_key=short  (too short)
 ```
 
 **Check 2: Key matches .env**
@@ -197,7 +186,7 @@ docker-compose logs aegis-mcp | tail -50
 
 Look for:
 - `invalid_api_key` → Key doesn't match
-- `missing_api_key` → Header not sent
+- `missing_api_key` → api_key not provided
 - `invalid_key_format` → Key too short
 
 ### Issue: "No repositories visible"
@@ -211,8 +200,7 @@ Look for:
 
 **Test manually:**
 ```bash
-curl -H "Authorization: Bearer YOUR_KEY" \
-     https://mcp.yourdomain.com/mcp/tool/call \
+curl "https://mcp.yourdomain.com/mcp/tool/call?api_key=YOUR_KEY" \
      -X POST \
      -H "Content-Type: application/json" \
      -d '{"tool": "list_repositories", "arguments": {}}'
@@ -241,8 +229,7 @@ Too many failed authentication attempts
 
 **Verify tools are registered:**
 ```bash
-curl -H "Authorization: Bearer YOUR_KEY" \
-     https://mcp.yourdomain.com/mcp/tools
+curl "https://mcp.yourdomain.com/mcp/tools?api_key=YOUR_KEY"
 ```
 
 Should return JSON with tools array.
@@ -320,8 +307,7 @@ You can call tools directly via API:
 
 ```bash
 # List repositories
-curl -X POST https://mcp.yourdomain.com/mcp/tool/call \
-  -H "Authorization: Bearer YOUR_KEY" \
+curl -X POST "https://mcp.yourdomain.com/mcp/tool/call?api_key=YOUR_KEY" \
   -H "Content-Type: application/json" \
   -d '{
     "tool": "list_repositories",
@@ -329,8 +315,7 @@ curl -X POST https://mcp.yourdomain.com/mcp/tool/call \
   }'
 
 # Get file contents
-curl -X POST https://mcp.yourdomain.com/mcp/tool/call \
-  -H "Authorization: Bearer YOUR_KEY" \
+curl -X POST "https://mcp.yourdomain.com/mcp/tool/call?api_key=YOUR_KEY" \
   -H "Content-Type: application/json" \
   -d '{
     "tool": "get_file_contents",
@@ -350,8 +335,7 @@ For automated workflows, you can integrate MCP tools into CI/CD:
 # Example GitHub Actions (future enhancement)
 - name: Sync to Gitea via MCP
   run: |
-    curl -X POST https://mcp.yourdomain.com/mcp/tool/call \
-      -H "Authorization: Bearer ${{ secrets.MCP_API_KEY }}" \
+    curl -X POST "https://mcp.yourdomain.com/mcp/tool/call?api_key=${{ secrets.MCP_API_KEY }}" \
       -H "Content-Type: application/json" \
       -d '{...}'
 ```
diff --git a/src/aegis_gitea_mcp/server.py b/src/aegis_gitea_mcp/server.py
index 5dcc282..1ae99c8 100644
--- a/src/aegis_gitea_mcp/server.py
+++ b/src/aegis_gitea_mcp/server.py
@@ -74,8 +74,8 @@ async def authenticate_request(request: Request, call_next):
     auth_header = request.headers.get("authorization")
     api_key = auth_validator.extract_bearer_token(auth_header)
 
-    # Fallback: allow API key via query parameter (for ChatGPT UI without headers)
-    if not api_key:
+    # Fallback: allow API key via query parameter only for MCP endpoints
+    if not api_key and request.url.path in {"/mcp/tools", "/mcp/tool/call", "/mcp/sse"}:
         api_key = request.query_params.get("api_key")
 
     # Validate API key