I'm suggesting a POTENTIAL_TOOLS.md file that is not loaded into the context, but which Claude knows the existence of. That file would be an exhaustive list of all the tools you use, but which would be too many tokens to have perpetually in the context.
Finally, Claude would know - while it's planning - to invoke a sub-agent to read that file with a high level idea of what it wants to do, and let the sub-agent identify the subset of relevant tools and return those to the main agent. Since it was the sub-agent that evaluated the huge file, the main agent would only have the handful of relevant tools in its context.
Way too frequently Claude goes, "The task is fully implemented, error free with tests passing and no bugs or issues!" and I have to reply "did you verify server build/log outputs with run-dev per CLAUDE.md". It immediately knows the command I am referencing from the instructions buried in its context already, notices an issue and then goes back and fixes it correctly the second time. Whenever it happens it instantly makes an agentic coding session go from feeling like breezy, effortless fun to pulling teeth.
I've started to design a subagent to handle chores after every task to avoid context pollution but it sounds like hooks are the missing piece I need to deterministically guarantee it will run every time instead of just when Claude feels the vibes are right.