Schema-first, Effect-first tool loop:
- 'tool({ description, parameters, success, execute })' constructs a fully
typed Tool. parameters and success are Effect Schemas; execute is typed
against them and returns Effect<Success, ToolFailure>. Handler dependencies
are closed over at construction time so the runtime never sees per-tool
services.
- 'ToolRuntime.run(client, { request, tools, maxSteps?, stopWhen? })' streams
the model, decodes tool-call inputs against parameters, dispatches to the
matching handler, encodes results against success, emits tool-result events,
appends assistant + tool messages, and re-streams. Stops on non-tool-calls
finish, maxSteps, or stopWhen.
- Three recoverable error paths emit tool-error events so the model can
self-correct: unknown tool name, input fails parameters Schema, handler
returns ToolFailure. Defects fail the stream.
- 'ToolFailure' added to the schema and exported as the single forced error
channel for handlers.
- Tool definitions on the LLMRequest are derived via toJsonSchemaDocument so
consumers don't write JSON Schema by hand.
8 deterministic fixture tests cover the loop, errors, maxSteps, stopWhen, and
parallel tool calls in one step.
Kit Langton
3a2cb7f8ac