How to use Claude Code subagents to parallelize development

As someone who's built a project in this space, this is incredibly unreliable. Subagents don't get a full system prompt (including stuff like CLAUDE.md directions) so they are flying very blind in your projects, and as such will tend to get derailed by their lack of knowledge of a project and veer into mock solutions and "let me just make a simpler solution that demonstrates X."

I advise people to only use subagents for stuff that is very compartmentalized because they're hard to monitor and prone to failure with complex codebases where agents live and die by project knowledge curated in files like CLAUDE.md. If your main Claude instance doesn't give a good handoff to a subagent, or a subagent doesn't give a good handback to the main Claude, shit will go sideways fast.

Also, don't lean on agents for refactoring. Their ability to refactor a codebase goes in the toilet pretty quickly.

I don't use subagents to do things, they're best for analysing things.

Like "evaluate the test coverage" or "check if the project follows the style guide".

This way the "main" context only gets the report and doesn't waste space on massive test outputs or reading multiple files.

This is only a problem if an agent is made in a lazy way (all of them).

Chat completion sends the full prompt history on every call.

I am working on my own coding agent and seeing massive improvements by rewriting history using either a smaller model or a freestanding call to the main one.

It really mitigates context poisoning.

There's a large body of research on context pruning/rewriting (I know because I'm knee deep in benchmarks in release prep for my context compiler), definitely don't ad hoc this.