Sonnet 5.5 makes everyday agent work a routing decision

The release in context

On 28 September 2026, Anthropic introduced Claude Sonnet 5.5, describing it as a faster, lower-cost complement to Opus 5.5 for well-defined work. The company cites coding and knowledge-work evaluations and acknowledges that benchmark results describe only part of capability. These are release claims from the supplier. They do not prove that a particular team should move all tasks to the new model.

The practical question is routing

The distinct issue is how a team separates ordinary implementation from work requiring sustained judgment. Suppose a developer needs a form label corrected, a flaky test investigated and a permission model redesigned. Sending all three through one default path simplifies operation but obscures differences in uncertainty and consequence. Our interpretation is that this launch invites a clearer routing policy: define which tasks can proceed with a narrow brief, which require another review and which must return to a human first.

That policy should use observable features. A copy change has a different impact from a change to customer access. A missing reproduction or unclear acceptance condition is a reason to gather evidence, rather than merely increasing a model setting. A fast agent can still spend considerable time implementing the wrong interpretation.

How to assess an everyday-work tier

Choose tasks from a recent backlog and remove sensitive information before a trial. Prepare the expected behavior and one realistic regression to avoid. Ask reviewers to assess the resulting change without being told which candidate produced it. Track reopenings alongside initial acceptance. This makes it harder for fluent explanations to conceal an incorrect patch and provides evidence beyond a subjective impression of speed.

Escalation also has a cost. If the first agent repeatedly hands incomplete work to a stronger agent, the combined path can become slower than starting with a better brief. Record why escalation happened: missing context, failed tools, contradictory requirements or genuine reasoning difficulty. Those categories lead to different fixes. Many routing problems are documentation problems in disguise.

The limits of the announcement

BijliCoin has not run a head-to-head Sonnet evaluation. Provider settings and access controls should be checked in the account a team actually uses. A release does not resolve code ownership, production approval or incident response. The useful outcome of a trial is a documented task class that works within a review budget, together with examples of when the system should stop. That is a stronger basis for adoption than assuming everyday work is automatically low risk.

Sources

• Claude Sonnet 5.5 announcement — 2026-09-28