# Agent Identity and Discovery (AID) vs Agent Discovery Protocol (ADP)

The map lists them as complementary: sites and agents commonly implement both.

[1 Discover](/category/discover/) [Agent Identity and Discovery](/protocols/aid/) · [1 Discover](/category/discover/) [Agent Discovery Protocol](/protocols/adp/)

|  | [Agent Identity and Discovery](/protocols/aid/) AID | [Agent Discovery Protocol](/protocols/adp/) ADP |
| --- | --- | --- |
| Lifecycle step | 1 Discover: What is here, and where? | 1 Discover: What is here, and where? |
| Answers | Given a domain, where is the agent and which protocol should I speak, with cryptographic proof the endpoint controls the matching key? | How does an agent escalate from a cheap DNS lookup, to a well-known JSON metadata document, to a real-time WebSocket session, using only as much machinery as the task needs? |
| Governed by | Agent Community open-source project; editor listed as 'Agent Community'; no formal standards body, though the spec discusses composing with IETF-track work (RFC 9421, RFC 7638, RFC 9728, RFC 8414) | IETF individual Internet-Draft; explicitly delegates its DNS layer to the separate dnsop-area DNS-AID draft rather than defining its own |
| Status (issuer's words) | Current normative specification | Internet-Draft; work in progress |
| Version | v2.1.0 (aid2 wire format; aid1 legacy) (2026-06-01) | draft-pro-adp-agent-discovery-02 (2026-07-24) |
| Form / transport | DNS record | well-known file |
| Found at | _agent.<domain> (DNS TXT); /.well-known/agent (HTTP fallback) | /.well-known/agent.json |
| Implementation | shipping | prototype |
| Evidence | 3 verified | 3 verified |
| Primary use case | Let agents discover my API or service | Let agents discover my API or service |
| Last verified | 2026-10-23 (current) | 2026-10-23 (current) |
| Specification | [https://raw.githubusercontent.com/agentcommunity/agent-identity-discovery/main/packages/docs/specification.md](https://raw.githubusercontent.com/agentcommunity/agent-identity-discovery/main/packages/docs/specification.md) | [https://datatracker.ietf.org/doc/html/draft-pro-adp-agent-discovery-02](https://datatracker.ietf.org/doc/html/draft-pro-adp-agent-discovery-02) |

## When to use which

- Choose Agent Identity and Discovery when your question is “Given a domain, where is the agent and which protocol should I speak, with cryptographic proof the endpoint controls the matching key?” and you accept its maturity: status "Current normative specification", implementation shipping.
- Choose Agent Discovery Protocol when your question is “How does an agent escalate from a cheap DNS lookup, to a well-known JSON metadata document, to a real-time WebSocket session, using only as much machinery as the task needs?” and you accept its maturity: status "Internet-Draft; work in progress", implementation prototype.

Guidance is derived from the two records (question, status, implementation, prerequisites, pairings), not from opinion. Each record's page carries its numbered references.

## Read the full articles

- [Agent Identity and Discovery](/protocols/aid/): Given a domain, where is the agent and which protocol should I speak, with cryptographic proof the endpoint controls the matching key?
- [Agent Discovery Protocol](/protocols/adp/): How does an agent escalate from a cheap DNS lookup, to a well-known JSON metadata document, to a real-time WebSocket session, using only as much machinery as the task needs?

Ask the MCP server to compare any two: the compare-protocols prompt, or get on both ids. [Connect](/connect/).

[aid.json](/data/protocols/aid.json) · [adp.json](/data/protocols/adp.json) · [Markdown](/compare/aid-vs-adp/index.md)