Claude Code limits retries that could repeat a tool’s side effects
Claude Code 2.1.307 fixes HTTP MCP tool calls being sent twice when a connection closes during a call. Automatic retries now apply only to read-only or idempotent tools—operations intended to be safe to repeat. The release also adds telemetry for tool calls stopped or escalated by safety controls. These changes make uncertain network outcomes and permission decisions easier to handle, without guaranteeing every external tool’s behavior.
Anthropic · Oct 21, 2026
Why it matters
A lost connection does not tell a client whether the server already completed a write operation.
More context
The official release notes document the retry change and a new claude_code.safety_event OpenTelemetry event. Try connection-failure handling with a disposable tool before relying on it for writes. Version 2.1.308 is newer and lists general reliability fixes; this card describes the substantive .307 change.
Keep in mind
The policy depends on tool properties and does not provide exactly-once execution across arbitrary services. The release notes are implementation claims, not an independent test of third-party MCP servers.
Original read