Open up the source code of any agent framework, harness, etc. Hermes, Copilot, Pi, Opencode or whatever.

You will find tools, tools everywhere.

Examples:

https://github.com/NousResearch/hermes-agent/tree/main/tools https://github.com/anomalyco/opencode/tree/dev/packages/opencode/src/tool

These are bash hooks, file viewers, file editors, greps, questions, tasks, web search.