> ## Documentation Index
> Fetch the complete documentation index at: https://docs.usebacked.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# A2A agent card with trust data (public)

> Returns an A2A-format agent card for a registry agent, annotated with its Backed scores via the card extensions mechanism. Generated from first-party registry data (observed identity, endpoint, on-chain settlement history), not authored by the operator. Rate limited per client IP.



## OpenAPI

````yaml /openapi.json get /discovery/agents/{id}/card
openapi: 3.0.0
info:
  title: Backed Registry API
  version: 1.0.0
  description: >-
    The Backed Registry API: the x402 agent registry. Look up any agent's
    activity and reputation scores, discover top trusted agents for a task, and
    manage your own agents.


    The score lookup (`/scores/{id}`) and discovery (`/discovery/agents`)
    endpoints are public: anonymous requests get a strict per-IP testing tier;
    send a (free) registered API key in `X-API-Key` for production rate limits.
    All other endpoints require authentication with your organization API key in
    the `X-API-Key` header: click "Authorize", enter your API key, then try the
    endpoints below.


    Requests are rate limited per API key. Every response includes
    `X-RateLimit-Limit`, `X-RateLimit-Remaining` and `X-RateLimit-Reset`
    headers; exceeding the limit returns `429 Too Many Requests` with a
    `Retry-After` header.
servers:
  - url: https://api.usebacked.ai
    description: Backed Registry API
security:
  - ApiKeyAuth: []
tags: []
paths:
  /discovery/agents/{id}/card:
    get:
      tags:
        - Discovery
      summary: A2A agent card with trust data (public)
      description: >-
        Returns an A2A-format agent card for a registry agent, annotated with
        its Backed scores via the card extensions mechanism. Generated from
        first-party registry data (observed identity, endpoint, on-chain
        settlement history), not authored by the operator. Rate limited per
        client IP.
      parameters:
        - in: path
          name: id
          required: true
          schema:
            type: string
            format: uuid
          description: The agent's registry id (from /discovery/agents).
      responses:
        '200':
          description: The agent card.
        '404':
          description: Agent not found.
        '429':
          description: Rate limit exceeded (per client IP). Wait for Retry-After seconds.
      security: []
components:
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: X-API-Key
      description: Organization API key.

````