Mouse-1 Turns Agent Choices Into API
Mouse-1 is a specialized decision model for agent harnesses that scores typed options from application state instead of generating prose. Its API handles up to 128 questions in roughly 100 milliseconds, with input priced at $0.10 per million tokens and free output.
Mouse-1 targets the overlooked control-flow layer of agents, where cheap, fast decisions can reduce frontier-model latency and cost without replacing deeper reasoning.
- –Scores tool routing, action gating, verification, and human-review decisions directly
- –Reports 89.1% accuracy on unfamiliar tools and repositories, though it trails d3 and Clef on its broader tool-and-security suite
- –Its claimed 0% decision-flip rate under planted prompt injection is promising, but not a substitute for end-to-end security testing
- –The strongest use case is pairing Mouse-1 with a frontier model: Mouse-1 handles repetitive branching while the larger model handles planning and code
- –Developers should validate calibration and failure costs inside real agent loops before trusting probabilities for irreversible actions
DISCOVERED
1h ago
2026-10-21
PUBLISHED
7h ago
2026-10-21
RELEVANCE
AUTHOR
Pete McGrath