---
title: "Troubleshooting"
description: "Missing API key: set `GESSA_API_KEY` for stdio clients."
engineVersion: v1.0.234
date: 2026-09-28
license: "(c) Gessa, proprietary. Cite with attribution to https://gessa.ai/docs/. Terms: https://gessa.ai/terms/."
canonical: https://gessa.ai/docs/creator/mcp/troubleshooting/
---
# Troubleshooting

Missing API key: set `GESSA_API_KEY` for stdio clients.

OAuth `invalid_target`: the token request `resource` must match the protected resource metadata `resource`.

403 from a tool call: the token or key lacks the required MCP scope.

No tools listed: verify the client is using stdio for local subprocess clients or `/mcp/rpc` for remote Streamable HTTP clients.