Protocols

Open Responses is an open specification and ecosystem, based on the OpenAI Responses API, that gives applications one shared schema for calling models, streaming results and composing agentic workflows across providers.

Large language modelsOpen sourceDeveloper tools

OpenEnv is an open framework and community hub from Hugging Face for building reinforcement-learning environments as containerized services that expose an agent interface, MCP and the Gym training protocol. It was contributed to the Agentic AI Foundation in October 2026.

Large language modelsOpen sourceDeveloper tools

GPT Actions let a custom GPT call external APIs, turning a user's request into the JSON input an API needs. Introduced by OpenAI on 6 November 2023, they grew out of the plugins beta and rely on OpenAPI schemas plus authentication settings.

Large language modelsEnterpriseDeveloper tools

Function calling, now also called tool calling, lets an application describe external functions to a model, which then decides whether to emit JSON arguments for one of them — the route by which models reach data and actions outside their training data.

Large language modelsAgents & tool useDeveloper tools

OWL is a W3C Recommendation published on 10 February 2004: a semantic markup language for publishing and sharing ontologies on the Web, giving software formal definitions of terms so it can process the meaning of information, not just display it.

Research historyOpen sourceData & datasets

OASF is a standardized, extensible schema system from the AGNTCY project for describing AI agent attributes, skills and capabilities in machine-readable records, so that agents can discover and understand each other across protocols.

Open sourceData & datasetsInteroperability