Independent This document specifies the Verifiable Agent Protocol (VAP), a thin, tool-agnostic verification layer for protocols in which an autonomous agent (a client driven by a large language model) invokes tools exposed by a server (for example, the Model Context Protocol, MCP). Existing tool-invocation protocols convey WHAT tool is to be run and, with authorization extensions, WHO is calling, but carry no machine- verifiable statement of WHY a call is being made. VAP adds a declared, structured, optionally signed statement of purpose and a stable per-session scope-and-budget commitment, against which a server performs admission control before executing a call. VAP defines four messages -- Scope Commitment, Intent Envelope, Scope Amendment, and Verdict -- carried inside the host protocol's existing metadata channel, requiring no change to that protocol and no change to existing servers. VAP targets erroneous and runaway agent behavior, session cost control, and audit; it is defense-in-depth for, not a replacement for, authentication and authorization.