Attest Registry
Querying the registry
No key is needed to read. Rate limit: 120 requests a minute per address. The same four tools are available over MCP and as REST.
Over MCP
| Endpoint | https://registry.cleartrust.cc/mcp |
| Transport | Streamable HTTP, stateless; POST one JSON-RPC message or a batch |
| Tools | search_agents · get_agent · check_authorization · list_verified · get_adcp_capabilities |
// tools/call
{ "name": "search_agents", "arguments": { "property_domain": "news.example", "verified_only": true } }
{ "name": "get_agent", "arguments": { "agent_url": "https://sales.news.example/mcp" } }
{ "name": "check_authorization", "arguments": { "agent_url": "https://sales.news.example/mcp", "property_domain": "news.example" } }Add it to a buying agent as any MCP server; a Claude or SDK client discovers the tools from tools/list.
Over REST
GET https://registry.cleartrust.cc/api/agents?q=news&type=sales&grade=A&verified=1&property=news.example&limit=50&offset=0 GET https://registry.cleartrust.cc/api/agents/<slug> GET https://registry.cleartrust.cc/api/authorization?agent_url=https://sales.news.example/mcp&property_domain=news.example
Answers are cached for a minute (five for authorisation). Every listing carries attest_verified, grade, mutual_count, specialisms, transports and the MCP and A2A endpoints.
Grades and the seal
| Grade | Means |
|---|---|
| A | Reachable and conformant; every claimed property mutually authorised; security storyboards clean. |
| B | Minor conformance gaps, or a property authorised on one side only. |
| C | Security, signing or schema storyboards failing, or most properties unverifiable. |
| D | Reachable, but no property authorises it on both sides, or capabilities missing. |
| F | Unreachable, or confirmed critical security findings. |
The Attest seal is grade A or B with at least one mutually authorised property. Treat it as a floor, not a purchase decision: the registry says who an agent is and whether its claims hold; Attest Verify says whether a specific buy should go ahead.
Authorisation checks
A publisher authorises a seller in /.well-known/adagents.json (authorized_agents[], optionally scoped by property_ids). The seller claims the property in its /.well-known/brand.json. check_authorization reads both live (cached a few hours) and answers mutual, publisher_only, not_listed, no_document or unverifiable, with the URLs it read as evidence.
How fresh it is
Listings are re-verified on a schedule (default every 7 days), whenever a cached brand.json or adagents.json changes (crawled every 6 hours), on the operator's request, and, once ClearTrust is enrolled, on events from the AgenticAdvertising.org change feed. Health is pinged hourly.