Declarations, runtime interfaces, scoped surfaces, input mutation, permission decisions, scheduling, progress, results, persistence, and audit links for tools used by agents.
Agent Tool is a portable standard for the tool layer in agent systems. It defines how tools are described, selected, invoked, authorized, scheduled, streamed, monitored, constrained, persisted, rendered, and returned without replacing MCP, OpenAPI, function calling APIs, runtime executors, UI renderers, policy engines, evidence archives, or artifact stores.
Use Agent Tool when a product needs stable semantics for capabilities such as file access, web search, browser control, shell commands, code execution, API calls, media generation, document extraction, tool search, MCP servers, peer-agent calls, and native application actions.