Frequent overloaded_error (529) on Opus 4.6 during subagent spawning

Description

Getting frequent 529 overloaded_error responses when using Claude Code with Opus 4.6 (1M context). The errors occur during normal usage — spawning subagents and recalling memory — and require multiple retries.

Error Details

{"type":"error","error":{"type":"overloaded_error","message":"Overloaded. https://docs.claude.com/en/api/errors"},"request_id":"req_011CZ9KaQhsMXNdx7kLJtY4S"}

{"type":"error","error":{"type":"overloaded_error","message":"Overloaded. https://docs.claude.com/en/api/errors"},"request_id":"req_011CZ9KrFwiU3mysNscn1PpE"}

Reproduction

• Model: claude-opus-4-6 (1M context)
• Action: Spawning Haiku subagents for web research + recalling memory files
• Retries observed: Up to attempt 7/10 before succeeding
• Time: ~2026-03-17 23:57 UTC+3
• Platform: macOS Darwin 25.3.0

Screenshot

The CLI showed:

Retrying in 5 seconds… (attempt 7/10)
Retrying in 1 second… (attempt 5/10)

Expected Behavior

API calls should succeed without requiring 5-7 retry attempts.

Notes

This may be a transient capacity issue on Anthropic's side rather than a Claude Code bug, but reporting for visibility since it directly impacts CLI usability.