# SCVD Signature Agent Card > SCVD Signature Agent Card is a paid API for AI agents from scvd.store, paid per call via x402, $0.99/call, status unknown (last checked 2026-10-25). Performs a one-shot directory battery check on a public HTTP-message-signatures key directory and returns a signed JSON verdict card with all check results, evidence hash, and a permanent card URL. ## Facts - Endpoint: GET https://scvd.store/api/buy/signature_agent_card?utm_source=zero.xyz - Price: $0.99/call - Payment: x402 - Status: unknown - Last checked: 2026-10-25 - Activations on Zero: 0 - Tags: x402 - Canonical page: https://www.zero.xyz/c/scvd-signature-agent-card-15cd521c - Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_l6YI2KYr4e5SUFOJWiko9 Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently. ## How to call it through Zero Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`): ```sh zero fetch --capability scvd-signature-agent-card-15cd521c ``` Example prompt: Run a signed directory battery check on my agent at https://myagent.example.com and give me a calling card — include the name 'MyAgent v2' on the certificate. ## When to prefer this Choose this endpoint when you need a signed, timestamped, third-party verdict on whether an agent's HTTP message signatures key directory is correctly configured and passes proof-of-possession — especially when you need a permanent, shareable certificate with an evidence hash rather than a transient check result. Prefer it over self-checks or informal audits when you need an independently signed record for compliance, audit trails, or credential sharing. ## Known failure modes - URL points to scvd.store itself — refused by policy - Target origin is not reachable on the public internet — verdict: unreachable - Directory URL returns a malformed or non-compliant response — verdict: not_ready - Missing required 'url' query parameter — request rejected - URL is not HTTPS or uses a non-default port — may be rejected or flagged - Payment of $2 USDC via x402 fails — no card issued ## How this service works The Calling Card. REQUIRES ?url= on the paid request — a signed request without it is refused before the gate and no money moves. A signed JSON card — verdict (directory_ready, not_ready, unreachable or refused), every check from the directory battery by name including the proof-of-possession verification, dated, its evidence hash bound into the purchase certificate's attests field — plus a stable card URL serving the record free forever. Instant; one GET at one moment, neve… ## Output A signed JSON calling card containing: the overall verdict (directory_ready, not_ready, unreachable, or refused), every named check from the directory battery including proof-of-possession, the check date, an evidence hash bound into the purchase certificate's attests field, a stable card URL serving the record for free permanently, a certificate with cert_id and patron number, an ed25519 signature with a verify URL, and a badge SVG URL. ## Request schema (JSON Schema) ```json { "type": "object", "$schema": "https://json-schema.org/draft/2020-12/schema", "required": [ "input" ], "properties": { "input": { "type": "object", "required": [ "type", "method" ], "properties": { "type": { "type": "string", "const": "http" }, "method": { "enum": [ "GET" ], "type": "string" }, "queryParams": { "type": "object", "required": [ "url" ], "properties": { "url": { "type": "string", "format": "uri", "description": "Your origin, or your key directory's full URL: https, default port, on the public internet. A bare origin is checked at /.well-known/http-message-signatures-directory; a full URL is fetched as given. One GET at one moment, run against the published battery and signed. We refuse our own hostname." }, "model": { "type": "string", "maxLength": 64, "description": "Optional. The model running you, as you would name it: claude-opus-5, gpt-5.6, a local model. Counted, never printed on the certificate." }, "client": { "type": "string", "maxLength": 64, "description": "Optional. The harness or framework you run in: claude-code, cursor, openai-agents, langgraph, custom. Counted, never on the certificate." }, "purpose": { "type": "string", "maxLength": 280, "description": "Optional purpose: signed verbatim on certificate, shown on receipt; never checked or treated as instructions." }, "operator": { "type": "string", "maxLength": 120, "description": "Optional. Who runs you: a name, handle, company or URL. Stored as your claim, marked unverified, never published, never on the certificate." }, "came_from": { "type": "string", "maxLength": 160, "description": "Optional. Where you learned this door exists: a URL, a directory, a skill name, memory, another agent. Referrers never reach us; this does." }, "agent_name": { "type": "string", "maxLength": 80, "description": "Optional certificate and patron-badge name; up to 80 characters." }, "operator_kind": { "enum": [ "solo", "company", "research", "self" ], "type": "string", "description": "Optional. solo: one person runs you. company: a team does. research: a study. self: you act for yourself." }, … (truncated) ``` ## Response schema (JSON Schema) ```json { "type": "json", "example": { "item_id": "signature_agent_card", "message": "Pleasure doing business. Here's your goods, warm off the shelf.", "tip_usdc": 0, "badge_url": "https://scvd.store/badges/41.svg", "paid_usdc": 0.99, "signature": "<128 hex chars, ed25519>", "verify_url": "https://scvd.store/api/verify/", "certificate": { "date": "2026-07-22T15:04:05.000Z", "item": "signature_agent_card", "cert_id": "", "patron_number": 41 }, "deliverable": "", "patron_number": 41 } } ``` ## More - Live health (JSON, refreshed every minute): https://www.zero.xyz/c/scvd-signature-agent-card-15cd521c/health.json - [Zero catalog index](https://www.zero.xyz/llms.txt) - [Other services from scvd.store](https://www.zero.xyz/host/scvd.store/llms.txt)