Moving code tasks to Sonnet 5.5: review the migration settings
Check the supported model and thinking configuration, then test one bug fix against existing behaviour before moving every task.
In brief
A model migration changes more than a label. Anthropic’s Sonnet 5.5 notes call out a new thinking configuration for integrations that previously switched thinking off.
A controlled migration catches unsupported settings and behavioural regressions before they affect a whole coding workflow.
Check configuration before changing the model
Anthropic states that users of the old thinking-off configuration need the supported between_tools setting before moving to Sonnet 5.5. Use the linked migration instructions for the complete request; do not invent a JSON field from the setting name alone.
Give a small reproducible bug
Provide the failing behaviour, expected result and relevant files. Ask for the smallest appropriate fix and a description of affected code. Keep secrets and production permissions out of the test environment.
Review a concrete diff
Run the project’s meaningful existing checks and inspect edge cases related to the change. Record failures and tests not run. A confident summary or a successful model response is not evidence that the build passed or a production issue was resolved.
Before you act
Use the current official migration guide for request syntax and supported platform. Do not copy an old configuration or infer that a model benchmark validates your application.
What to do next
- Read the current migration guide for your existing configuration.
- Test one bounded code task in a recoverable branch or checkout.
- Review the diff, existing tests and actual behaviour before adopting the migration.
