ValidationErrorResponse

Body validation failure. Unknown top-level keys are rejected — the validator runs in
strict allowlist mode (allowUnknown: false), so a field not declared in the request
schema produces an unexpected_key detail rather than being ignored.

{
    "success": false,
    "error": {
        "code": "validation_failed",
        "message": "Request validation failed",
        "details": "string"
    },
    "timestamp": 1767225600000
}