AgentCard (agent payments)

AgentCard gives your Liminal agent capped single-use virtual cards, an @agentcard.email inbox, and a Base USDC wallet for x402 payments — under spend limits you control.

Canonical skill: https://agentcard.ai/skill

Harness integration

When AGENT_AGENTCARD=1 (default), the sidecar registers the agentcard tool family (19 tools). Activate with activate_tool_family({ family: "agentcard" }) when lazy loading is on, or mention payments/checkout in your message (intent pre-seed).

Tool	Purpose
agentcard_whoami	Current login
agentcard_signup	Magic-link signup (approval)
agentcard_setup	Profile + Stripe + inbox + wallet (approval)
agentcard_limit	Show spend limit
agentcard_limit_request	Request higher limit (approval + email)
agentcard_card_request	Issue capped virtual card (approval)
agentcard_card_list / agentcard_card_get	List / re-fetch card details
agentcard_3ds	Checkout verification codes
agentcard_mail_*	Agent email inbox
agentcard_wallet_*	Base USDC balance, x402 fetch, send
agentcard_support	Report declines / errors

Card issuance, wallet payments, signup, and limit changes are approval-gated.

One-time setup (sidecar host)

npm install -g agentcard
agentcard signup --email you@example.com
agentcard setup
agentcard whoami

Install the CLI on the same machine that runs the Liminal sidecar. Set AGENT_AGENTCARD_CMD if the binary is not on PATH.

Environment

Variable	Default	Purpose
AGENT_AGENTCARD	1	Register agentcard_* tools
AGENT_AGENTCARD_CMD	agentcard	CLI executable
AGENT_AGENTCARD_TIMEOUT_MS	120000	Per-call timeout (except signup)
AGENT_AGENTCARD_SIGNUP_TIMEOUT_MS	330000	Signup magic-link poll timeout

Disable with AGENT_AGENTCARD=0.

Agent workflow

1. agentcard_limit — check budget
2. Choose path: card checkout → agentcard_card_request; x402 API → agentcard_wallet_fetch; USDC → agentcard_wallet_send
3. At checkout: use card fields at merchant; if 3DS → agentcard_3ds
4. On failure → agentcard_support

Do not use run_shell agentcard … — use the dedicated tools (rule R-AGENTCARD).