if you're interested in an open source agent that uses a minimal amount of CPU and RAM and has source that is easy to audit:
https://github.com/smol-env/smol
here are traces from an agentic task around using duckduckdb
comparing CPU and RAM usage of the whole container over time w/ OpenCode, hermes, pi, codex, smol
https://x.com/__tosh/status/2086882367126286466
https://x.com/__tosh/status/2086882204060160350
smol is very minimal only using stdlib (in this case it is the go version but you can also take a look at implementations in python, clojure, php)
also no need to trust these bench runs, you can just run your own
(any OpenAI Responses API compatible endpoint works, if your endpoint does not support 'custom' tools you can have your agent change the smol implementation to use 'function' tool implementation instead)
that said: be aware that smol does not come with any system prompt and does not load agents.md files by default
some older not so strong models benefit from a system prompt and guidance in agents.md that complements them
that said 2: system prompt and or loading agents.md automatically is easy to add though if you want it
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