A Standard Schema (e.g. a Zod 4 schema) describing the tool's input.
OptionalneedsWhether this tool requires approval before executing. May be a static
boolean or a predicate evaluated per-call (e.g. keying off ctx.trust).
OptionaloutputAn optional Standard Schema describing the tool's output.
OptionalresultTrust level stamped onto this tool's result Parts. Tools returning
content fetched from outside the process (MCP, workspace reads, GitHub)
should set 'untrusted'.
A typed tool a Provider can be offered and the agent loop can execute.