---
title: Errors and limits
description: Handle Sift failures without unsafe retries or hidden partial success.
product: platform
lifecycle: stable
appliesTo: CLI and MCP public error contract
sourceArtifact: agent-contract@current
owner: Platform owner
raw: /raw/platform/errors-and-limits.md
---

Public failures include authentication, missing contract, unavailable tool, validation, permission, conflict, not found, retriable upstream failure, and internal failure. Preserve the structured error code and request ID when contacting support.

Retry read-only upstream failures with bounded backoff. Do not blindly retry writes: use idempotency, reread on conflict, and preserve explicit user intent. Size and pagination limits are exposed in each tool schema; use handles/cursors instead of requesting unbounded content.