skillspec

SkillSpec is an open-source CLI and contract format that transforms vague skill instructions into structured, enforceable plans. Instead of hoping an LLM follows free-form prose, SkillSpec extracts key steps, tools, and checks into a machine-readable contract. Agents then execute the contract step by step, generating cryptographic proof of compliance. Designed for agent developers and teams deploying AI at scale, SkillSpec works with any agent harness. It reduces token waste by only loading relevant steps, prevents instruction drift, and provides audit trails. The tool addresses the growing trust and security gaps in large skill catalogs, where nearly half of skills share names and adversarial variants win 77.6% of selection trials. Key features include Doctor risk reports that quantify execution drift, import guidance to convert prose into contracts, and alignment proofs that verify step execution. SkillSpec also enforces tool-use constraints and provides a replayable decision trace, making it suitable for compliance-heavy environments. The open standard encourages community verification and integration with existing frameworks. Unlike alternative approaches that rely on better prompting or verbose instructions, SkillSpec enforces execution fidelity through contracts. It quantifies risk, guides users through importing existing skills, and outputs alignment proofs. This makes it a strong choice for security-conscious teams who need more than a prompt—they need proof.