I'd add to that that every tool should have --json (and possibly --output-schema flags), where the latter returns a Typescript / Pydantic / whatever type definition, not a bloated, token-inefficient JSON schema. Information that those exist should be centralized in one place.

This way, agents can either choose to execute tools directly (bringing output into context), or to run them via a script (or just by piping to jq), which allows for precise arithmetic calculations and further context debloating.