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ichiorca

Ucp Checkout A2a

by Rohit Bajaj · GitHub ↗ · v1.0.0 · MIT-0
cross-platform ✓ Security Clean
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Install in OpenClaw
/install ucp-checkout-a2a
Description
Implement UCP Checkout over the A2A (Agent-to-Agent) binding — enable autonomous agent-to-agent commerce using Agent Cards and structured message parts. Use...
README (SKILL.md)

UCP Checkout — A2A Binding

Before writing code

Fetch live spec: Web-search site:ucp.dev specification checkout-a2a and fetch the page for the exact message structure, DataPart keys, and Agent Card format.

Also review Google's A2A protocol spec for the underlying transport: https://google.github.io/A2A/

Conceptual Architecture

What is A2A?

A2A (Agent-to-Agent) is a protocol for autonomous inter-agent communication. UCP's A2A binding lets a Platform agent talk to a Business agent using structured messages rather than REST calls.

How It Works

  1. Discovery: Business publishes an Agent Card at the URL declared in their /.well-known/ucp profile under services.dev.ucp.shopping.a2a.endpoint.
  2. Communication: Platform sends messages with checkout data in DataPart objects. Business agent responds with checkout state in DataPart objects.
  3. Identification: Platform includes UCP-Agent header and X-A2A-Extensions header referencing the UCP spec version.

Key Data Part Keys

Key Direction Purpose
a2a.ucp.checkout Both Checkout session data
a2a.ucp.checkout.payment_data Platform → Business Payment credentials for completion
a2a.ucp.checkout.risk_signals Platform → Business Optional risk signals
ap2.merchant_authorization Business → Platform Merchant's JWS detached content signature for AP2 mandate flow
ap2.checkout_mandate Platform → Business SD-JWT+kb credential proving user-authorized agent checkout

Message Structure

Messages use A2A's standard format:

  • messageId: Unique ID (used for idempotency)
  • contextId: Session/conversation ID
  • kind: "message"
  • role: "user" (from platform) or "agent" (from business)
  • parts: Array of TextPart and DataPart objects

Checkout data is carried in DataPart with the appropriate key.

Idempotency

The Business agent uses messageId to detect duplicate requests. Task tracking uses taskId with contextId.

When to Use A2A

  • Fully autonomous agent-to-agent commerce (no human in the loop for most steps)
  • Multi-agent architectures where commerce is one capability among many
  • When you want the Business to maintain its own agent logic (not just expose tools)

Implementation Guidance

Before implementing, fetch the latest sample A2A Business Agent from https://github.com/Universal-Commerce-Protocol/samples (look for the a2a/ directory) to see the reference pattern.

Usage Guidance
This skill appears to be a benign developer guide, not executable malware. Before using it for real commerce, make sure any implementation requires clear user authorization, limits spending and merchants, protects payment credentials, validates agent identities, and pins the external specs or sample code it relies on.
Capability Analysis
Type: OpenClaw Skill Name: ucp-checkout-a2a Version: 1.0.0 The skill bundle provides architectural guidance and protocol specifications for implementing Agent-to-Agent (A2A) commerce via the Universal Commerce Protocol (UCP). It contains no executable code and directs the agent to legitimate external documentation and sample repositories (ucp.dev, google.github.io, and github.com). The instructions in SKILL.md are consistent with the stated purpose of building commerce flows and do not exhibit signs of malicious intent or prompt injection attacks.
Capability Tags
cryptocan-make-purchases
Capability Assessment
ℹ Purpose & Capability
The skill purpose is coherent with UCP Checkout over A2A, and the commerce/payment-related behavior is disclosed, but checkout automation is inherently high-impact.
ℹ Instruction Scope
The instructions are developer guidance rather than executable code, but they encourage autonomous commerce flows and should be implemented with explicit user approval, spending limits, and merchant scoping.
✓ Install Mechanism
There is no install spec, no code, no required binaries, and no required environment variables; the artifact is instruction-only.
ℹ Credentials
The skill asks the agent to fetch live specifications and sample code from external sites, which is expected for implementing a protocol but should be reviewed for provenance before use.
ℹ Persistence & Privilege
No persistence or local privilege escalation is shown, but the described protocol includes payment data and authorization credentials that must be handled as sensitive.
How to Use
  1. Make sure OpenClaw is installed (local or Docker)
  2. Run the install command in chat: /install ucp-checkout-a2a
  3. After installation, invoke the skill by name or use /ucp-checkout-a2a
  4. Provide required inputs per the skill's parameter spec and get structured output
Version History
v1.0.0
Initial release of ucp-checkout-a2a — enables agent-to-agent autonomous checkout via UCP's A2A binding. - Implements checkout flow using structured A2A messages and Agent Cards. - Details message format, key DataPart keys, and session management. - Provides guidance for spec lookup and reference sample implementation. - Suitable for building fully autonomous, multi-agent commerce flows.
Metadata
Slug ucp-checkout-a2a
Version 1.0.0
License MIT-0
All-time Installs 0
Active Installs 0
Total Versions 1
Frequently Asked Questions

What is Ucp Checkout A2a?

Implement UCP Checkout over the A2A (Agent-to-Agent) binding — enable autonomous agent-to-agent commerce using Agent Cards and structured message parts. Use... It is an AI Agent Skill for Claude Code / OpenClaw, with 83 downloads so far.

How do I install Ucp Checkout A2a?

Run "/install ucp-checkout-a2a" in the OpenClaw or Claude Code chat to install it in one step — no extra setup required.

Is Ucp Checkout A2a free?

Yes, Ucp Checkout A2a is completely free, licensed under MIT-0. You can download, install and use it at no cost.

Which platforms does Ucp Checkout A2a support?

Ucp Checkout A2a is cross-platform and runs anywhere OpenClaw / Claude Code is available (cross-platform).

Who created Ucp Checkout A2a?

It is built and maintained by Rohit Bajaj (@ichiorca); the current version is v1.0.0.

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