fix: surface MCPProtocolError message via LocalizedError

[datlechin]

Summary

MCPProtocolError carries a message: String that holds the underlying SQL or transport detail (e.g., "Unknown column 'active' in 'field list'"), but the type didn't conform to LocalizedError. Error.localizedDescription therefore fell back to the Swift default formatter, which produces uninformative text like:

TablePro.MCPProtocolError error 1

This is what the AI chat user sees when a tool call fails, so the assistant has nothing to explain back beyond a generic guess at "connection issues / permissions / column existence".

Fix

Conform MCPProtocolError to LocalizedError and return message from errorDescription. Single-line change.

Effect

error.localizedDescription now returns the protocol's own message string. The chat tool result already uses localizedDescription when wrapping the failure, so failures like:

"Unknown column 'active' in 'field list'"
"Connection refused"
"User declined to run this query."

now surface verbatim instead of being masked.

Test plan

• Build the project.
• In AI Chat, ask the assistant to update users set is_inactive = 1 where id = 1 against a database where is_inactive does not exist.
• Tool result content shows "Error: Unknown column 'is_inactive' in 'field list'" (or the equivalent error from the underlying driver), not "TablePro.MCPProtocolError error 1".

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.