Agent-as-a-Tool — References

Interface specifications for exposing a capability behind a typed call, and the research on models selecting and invoking such calls.

Invocation interfaces

• Model Context Protocol — tool declaration, invocation, and result semantics between a client and a server, including how a server advertises what it offers.
• JSON-RPC 2.0 Specification — request, response, and error-object semantics; the error-object design is a useful model for a closed set of failure statuses.
• OpenAPI Specification — describing an operation's parameters, responses, and error codes in a form clients can generate against.
• Agent2Agent (A2A) protocol — task submission, status polling, and artefact return for agents invoked across ownership boundaries, which is the handle-and-poll shape raised to a protocol. Named here without a URL, as its hosting location has changed.

Models calling things

• Toolformer: Language Models Can Teach Themselves to Use Tools (Schick et al., 2023), arXiv:2302.04761 — how a model learns when a call is worth making, which is the behaviour a tool description is trying to influence.

Retry safety at the boundary

• RFC 9110: HTTP Semantics — the definitions of safe and idempotent methods, and why a caller cannot retry an operation whose idempotency it has not been told about.