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.

Totally agreed, tried agents for a lot of stuff (I started creating a team of agents, architect, frontend coder, backend coder and QA). Spent around 50 USD on a failed project, context contaminated and the project eventually had to be re-written.

Then I moved some parts in rules, some parts in slash commands and then I got much better results.

The subagents are like a freelance contractors (I know, I have been one very recently) Good when they need little handoff (Not possible in realtime), little overseeing and their results are a good advice not an action. They don't know what you are doing, they don't care what you do with the info they produce. They just do the work for you while you do something else, or wait for them to produce independent results. They come and go with little knowledge of existing functionalities, but good on their own.

Here are 3 agents I still keep and one I am working on.

1: Scaffolding: Now I create (and sometimes destroy) a lot of new projects. I use a scaffolding agents when I am trying something new. They start with fresh one line instruction to what to scaffold (e.g. a New docker container with Hono and Postgres connection, or a new cloudflare worker which will connect to R2, D1 and AI Gateway, or a AWS Serverless API Gateway with SQS that does this that and that), where to deploy. At the end of the day they setup the project with structure, create a Github Repo and commit it for me. I will take it forward from them

2: Triage: When I face some issues which is not obvious from reading code alone, I give them the place, some logs and the agent will use whatever available (including the DB Data) to make a best guess of why this issue happens. I often found out they work best when they are not biased by recent work

3: Pre-Release Check QA: Now this QA will test the entire system (Essentially calling all integration and end-to-end test suite to make sure this product doesn't break anything existing. Now I am adding a functionality to let them see original business requirement and see if the code satisfies it or not. I want this agent to be my advisor to help me decide if something goes to release pipeline or not.

4: Web search (Experimental) Sometimes, some search are too costly for existing token, and we only need the end result, not what they search and those 10 pages it found out...