Summary

The industry-standard 30-second cache keepalive interval for agentic AI workflows costs 8× more than necessary; empirical measurement across Anthropic, OpenAI, Gemini, and DeepSeek shows the optimal interval is roughly 4 minutes on Anthropic and 8 minutes on OpenAI. Keepalives only save money inside a 'paying band' — when the agent's idle pause exceeds the provider's eviction point but stays under the break-even horizon — and pings fired past the provider's TTL actively multiply costs rather than reducing them. DeepSeek and Gemini never save on cost via keepalives (only latency), and a single global interval across providers is always wrong.

Key Insight

Cache keepalive intervals must be tuned per-provider to just under the measured TTL, and abandoned entirely once idle pauses exceed the break-even horizon — the universal 30-second convention is never optimal and often actively harmful.

Spicy Quotes (click to share)

• 8

  The convention is to ping every 30 seconds. That convention costs 8× more than necessary.

• 4

  Keep the cache warm only when your pause is longer than the provider's eviction point but shorter than its break-even horizon. Inside that window the keepalive pays.

• 7

  An interval past the TTL is not merely wasteful. Every ping pays the exact penalty it was meant to avoid.

• 7

  A multi-provider agent that uses one global ping interval is either overpaying on OpenAI or burning money on Anthropic.

• 6

  The arbitrage is real, and it has an expiry date.

Tone

analytical