I wrote clark-agent, a small Rust library for running LLM tool loops.

The loop is:

context -> model -> tool call -> tool result -> repeat

The parts I wanted typed were:

- transcript messages - tool calls - tool results - stream events - tool schemas

The model/provider boundary is a StreamFn trait. Tools implement AgentTool. There are hooks for things like context transforms, tool gates, observers, and follow-up messages.