Sonnet 5.5: evaluating efficiency in everyday agent workflows

Follow the release timeline

Anthropic announced Sonnet 5.5 on September 28, emphasizing everyday coding, document work and collaboration. Its October 7 Haiku announcement then reduced Sonnet 5.5 cache reads to $0.10 per million tokens. Source 1 Source 2

Separate token prices from task costs

At verification, standard input and output prices are $2 and $10 per million tokens. Effort, context reuse, tool calls and retries still change the bill. The speed and cost improvements in the release are vendor measurements, not universal results for every application.

Our analysis: route by the work

A well-defined bug fix differs from an open-ended system investigation. Give routine jobs explicit acceptance criteria, then escalate when those criteria are not met. Completion quality and total cost should determine the routing policy.

Run a comparable migration test

Keep inputs, tool versions and output checks consistent. Include missing documents, tool failures and long conversations as well as successful examples. Record end-to-end latency, rather than output speed alone. For code changes, review whether unrelated behavior changed even when the test suite passes.

Confirm the actual integration

This article contains no independent Youjie benchmark. Verify the provider’s model identifier, supported parameters, context limits and quotas before shifting traffic. Start with a small rollout and preserve a known working fallback.