Assay

Assay is an open-source MCP (Model Context Protocol) server that acts as a firewall and trust compiler for AI agent tool calls. It enables deterministic policy enforcement, allowing or denying calls from agents (such as read_file, exec, or web_search) based on user-supplied policies, and produces cryptographically verifiable evidence bundles and trust artifacts for audit and compliance. Assay integrates with any MCP-compatible client (e.g., Claude Desktop, Cursor, Windsurf) and tools, fitting into CI pipelines and agent governance workflows to ensure provable, reviewable agent behavior without a hosted backend.