A tool error comes back with isError: true and the code in structuredContent.error.code.

Code	Means
`not_logged_in`	HTTP 401. No key, a bad key or a revoked key. Carries `loginUrl` and a `pairing`.
`rate_limited`	Too many calls. Wait `retryAfterSec` seconds. 60 calls a minute per key.
`limit_exceeded`	A deploy limit is over its ceiling. Names the field and the ceiling.
`not_supported`	That venue cannot be deployed from MCP yet.
`not_found`	No such id, or it belongs to someone else.
`refused`	Krexa said no to the request. The message says why.
`untradable_symbol`	Krexa cannot price or trade that coin on that venue.
`harness_unavailable`	The engine is down for a moment. Try again.

Errors