STE MCP Troubleshooting

Having trouble with the STE MCP? Use the table below to jump to your issue.

1. Cannot reach the MCP server

Symptom: "The MCP server couldn't be reached" or a connection failure on the first call.

Cause: Your network is blocking outbound traffic to mcp.symmetry.com. This is common with corporate VPNs that have split-tunneling misconfigured.

Resolution:

1. Try from a different network (home Wi-Fi or a mobile hotspot) to isolate whether the issue is network-specific.
2. If it works off-VPN but not on, ask your IT team to allow traffic to mcp.symmetry.com.

2. redirect_mismatch after sign-in

Symptom: The browser opens and you sign in successfully, but you see redirect_mismatch or invalid_redirect_uri.

Cause: Symmetry's OAuth allowlist only accepts port 33418 as a redirect target. If your client uses a different port, the auth flow fails.

Resolution:

Claude Code — Remove and re-add the MCP with the --callback-port flag, then restart:

claude mcp remove ste
claude mcp add ste --transport http https://mcp.symmetry.com/ste --callback-port 33418

Restart Claude Code after running these commands.

Cursor — This is unusual; Cursor uses port 33418 by default. Open Developer Tools → Console and check the actual redirect URL it attempted, then update accordingly.

Gemini CLI — Confirm your settings.json has redirectUri set explicitly:

"redirectUri": "http://localhost:33418/oauth/callback"

3. Tools not showing up after installation

Symptom: "The ste MCP isn't available" even though you just added it.

Cause: The MCP was registered but the client session hasn't reloaded it yet.

Resolution:

• Cursor: Go to Settings → MCP and check that ste has a green dot. If it's red or yellow, click into it to see the error message.
• Claude Code: Run claude mcp list to confirm ste is registered. If it appears in the list but tools aren't available in your current chat, you need to restart. Exit the session (/exit or close the terminal) and start a fresh one.
• Gemini CLI: Confirm your settings.json is valid JSON (no trailing commas, all brackets closed), then restart the CLI.

  Note: Claude Code only loads MCPs at startup. Any time you add, remove, or change an MCP, you must restart the session.

4. Token expired / prompted to sign in again

Symptom: "Token expired" or an unexpected browser sign-in prompt mid-session.

Cause: Access tokens live for 60 minutes; refresh tokens live for 24 hours. After 24 hours of inactivity, the full sign-in flow repeats.

Resolution: This is expected behavior. Complete the sign-in flow in the browser — the tab closes automatically after authentication and your client resumes where it left off.

Token lifetime cannot be extended. This is by design for security.

5. 403 / Request blocked

Symptom: A tool call fails with a 403 "Request blocked" error.

Cause: Symmetry's edge security filter blocked the request. The two most common triggers are a request body over 64 KB, or content that resembles suspicious patterns (for example, SQL-like strings).

Resolution:

• Check whether the request body is unusually large — multi-employee batch calls can hit the limit.
• If the request looks well-formed and small, share the failing request and timestamp with our team and we'll help troubleshoot.

6. Removing or resetting the STE MCP

Use this when you need to disconnect, reconfigure, or start fresh.

Cursor: Go to Settings → MCP, click the ste entry, and select Remove. Or delete the ste key from ~/.cursor/mcp.json.

Claude Code:

claude mcp remove ste

Restart Claude Code after running this command.

Gemini CLI: Remove the ste-mcp block from ~/.gemini/settings.json and restart the CLI.

Still stuck?

If none of the above resolves your issue, reach out to our team with:

• A description of the error
• The client you're using
• The failing request payload and timestamp (if available)
  For authentication issues, include the full error message shown in the browser or terminal.