# Agentic Resource Discovery (ARD) vs agents.txt

They sit at the same step and overlap in purpose; the fields above are the basis for choosing.

[1 Discover](/category/discover/) [Agentic Resource Discovery](/protocols/ard/) · [1 Discover](/category/discover/) [agents.txt](/protocols/agents-txt/)

|  | [Agentic Resource Discovery](/protocols/ard/) ARD | [agents.txt](/protocols/agents-txt/) |
| --- | --- | --- |
| Lifecycle step | 1 Discover: What is here, and where? | 1 Discover: What is here, and where? |
| Answers | Where are an organization's discoverable agentic resources (MCP servers, A2A agents, skills, registries), and how can they be found by search rather than pre-installed one at a time? | Which agent-facing protocols (payments, auth, MCP, skills, A2A) does this site speak, and where? |
| Governed by | Authored by individuals at Google, Microsoft and Hugging Face (Junjie Bu, R.V. Guha, Shaun Smith); published as an open GitHub project (ards-project/ard-spec) with no formal standards body yet; contributions acknowledged from AWS, Cisco, Databricks, GitHub, GoDaddy, Nvidia, Salesforce and Snowflake | None; at least three non-converging proposals (agents-txt.com, kaylacar/agents-txt, agentstxt.dev) each self-describe as "the" agents.txt standard, with no shared maintainer or reconciliation process found |
| Status (issuer's words) | Proposal | "An open standard proposal for declaring what AI agents can do on a website" (kaylacar/agents-txt); a Mastercard developer-documentation page independently characterizes the space as "IETF draft expired ... fragmented landscape with 11+ competing proposals ... no ratified standard" |
| Version | v0.91 (2026-08-26) | agents-txt.com: v1.0; competing proposals carry no shared version |
| Form / transport | well-known file | well-known file |
| Found at | /.well-known/ard.json | /agents.txt (well-known root path per all identified proposals; one proposal also allows /.well-known/agents.txt) |
| Implementation | multi-implementation — agenticweb.wiki /check/ probe (13/268 origins on /.well-known/ard.json; 43/268 on predecessor /.well-known/ai-catalog.json) | prototype |
| Evidence | 2 verified, 2 reported | 3 verified, 1 reported |
| 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/ards-project/ard-spec/main/spec/ard.md](https://raw.githubusercontent.com/ards-project/ard-spec/main/spec/ard.md) | [https://agents-txt.com/spec](https://agents-txt.com/spec) |

## When to use which

- Choose Agentic Resource Discovery when your question is “Where are an organization's discoverable agentic resources (MCP servers, A2A agents, skills, registries), and how can they be found by search rather than pre-installed one at a time?” and you accept its maturity: status "Proposal", implementation multi-implementation (agenticweb.wiki /check/ probe (13/268 origins on /.well-known/ard.json; 43/268 on predecessor /.well-known/ai-catalog.json)).
- Choose agents.txt when your question is “Which agent-facing protocols (payments, auth, MCP, skills, A2A) does this site speak, and where?” and you accept its maturity: status ""An open standard proposal for declaring what AI agents can do on a website" (kaylacar/agents-txt); a Mastercard developer-documentation page independently characterizes the space as "IETF draft expired ... fragmented landscape with 11+ competing proposals ... no ratified standard"", 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

- [Agentic Resource Discovery](/protocols/ard/): Where are an organization's discoverable agentic resources (MCP servers, A2A agents, skills, registries), and how can they be found by search rather than pre-installed one at a time?
- [agents.txt](/protocols/agents-txt/): Which agent-facing protocols (payments, auth, MCP, skills, A2A) does this site speak, and where?

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

[ard.json](/data/protocols/ard.json) · [agents-txt.json](/data/protocols/agents-txt.json) · [Markdown](/compare/ard-vs-agents-txt/index.md)