MCP error codes
Every public API error code emitted by MCP, with its HTTP status, its type and a page per code.
Error codes emitted by MCP. Each code links to its own page with the cause and the action to take.
| Code | Type | HTTP | Description |
|---|---|---|---|
mcp_guardrail_violation | invalid_request_error | 422 | The call breaks a declared tax rule and was rejected LOCALLY, before anything ran: no document was created, modified or deleted. It is the only code in the catalogue that no API v1 route can emit — whoever receives it is talking over MCP. The subcode says which of the nine guardrails was broken, and the error data carries guardrail_uri (the resource that explains the rule) and rule_id (the specific rule, shaped BR-XXX-NNN). |
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Error codes by category
Find an error by the category that emits it.
Full reference table
All codes, HTTP statuses, types and descriptions in one reference.
Error model
Interpret the error envelope and handle errors by code.