AgentIDL

AgentIDL is an open specification extending W3C WebIDL to describe semantic agents — autonomous computational entities with verifiable identities, capabilities, intents, and delegations.

It provides a bridge between ontological definitions (RDF/OWL/JSON-LD) and executable interfaces for agent frameworks, allowing semantic interoperability across AI systems and protocols.

Why AgentIDL

• Adds semantic annotations ([Intent], [Proof], [Capability], [Context]) to standard WebIDL interface definitions.
• Generates machine-readable bindings (JSON-LD / TTL) aligned with W3C Agent Ontology.
• Enables code generation for multiple runtimes (TypeScript, Python, Rust).
• Integrates with Nix-based build environments and W3C Semantic Agent Communication CG.

Example

[[
  Context = "https://s-agent-comm.github.io/agent-ontology/context/agent.jsonld",
  Semantic = "https://s-agent-comm.github.io/agent-ontology/ontologies/intent.ttl"
]]
interface AgentTask {
  [Intent="agent:ProposeContract"]
  Promise<Outcome> proposeContract(ContractData data);

  [Intent="agent:ExecutePayment", Proof="ledger:tx"]
  Promise<Receipt> executePayment(PaymentRequest payment);
};

Positioning: A Bridge Between Semantics and Execution

While the ontology layer describes what an agent is (roles, capabilities, contracts, etc.), AgentIDL defines how an agent acts and speaks. It serves as a "Semantic API" that can be compared to:

• OpenAPI/IDL for the web, but operating at a semantic level.
• gRPC's .proto files, but with support for intents, trust, and grammar.
• Solidity's function signatures, but for agent behavioral protocols.

Semantically, it combines:

Ontology (meaning) + Grammar (syntax) + Protocol (execution)

This creates an agent-level Application Behavior Interface (ABI).

Comparison

	Semantic Definition (Ontology)	Execution Interface (Interface)
Purpose	Defines the concepts and their relationships	Defines the methods and their signatures
Format	.ttl, .jsonld, .shacl	.idl, .jsonld, .ts
Toolchain	RDF / Jena / pySHACL	WebIDL2.js / Node / Nix
Publication	gh-pages + w3id	npm + gh-pages (docs)
Boundary	Semantic correctness, conceptual consistency	Behavioral consistency, semantic mapping
Coupling	ontology v1.0	idl v1.0 → imports ontology v1.0