How do I write instructions that Cosmos does well?

Cosmos does best with what a teammate would need.

A good example#

Create a small Express API in a folder named todo-api with GET/POST /todos
backed by SQLite. Add tests with node:test and run them.
Done means: all tests pass. Reply with the test output and how to start the server.

Checklist#

• Say what "done" looks like. "Run the tests and show me the output" beats "make sure it works".
• Name files and folders you care about.
• Put limits in the instructions: "don't add dependencies", "keep it under 100 lines".
• Paste what it needs: a spec, an error log or a snippet. input takes up to 20,000 characters.
• Ask for outputs by name: "Save the final script as an output named sync.py."

Avoid#

• Vague goals ("improve the app").
• Secrets in input. Connect services to your account instead.

See Your first real run.