I’d like to add: keep some kind of development documentation where you describe in detail the patterns and architecture of your application and it’s components.

I’ve seen incredible improvements just by doing this and using precise prompting to get Claude to implement full services by itself, tests included. Of course it requires manual correction later but just telling Claude to check the development documentation before starting work on a feature prevents most hallucinations (that and telling it to use the Context7 MCP for external documentation), at least in my experience.

The downside to this is that 30% of your context window will be filled with documentation but hey, at least it won’t hallucinate API methods or completely forget that it shouldn’t reimplement something.

Just my 2 cents.