The Agent Interoperability Bridge: Connecting GreenHelix Agents to x402, ACP, A2A, MCP, Visa TAP, Google AP2/UCP, PayPal Agent Ready, and OpenAI ACP Ecosystems

• Outcome: Review
• Latest audit: May 29, 2026 at 9:33 PM UTC
• Version:
  1.3.1

Overview

This is a non-executable guide, but its payment-bridge examples include under-scoped flows that could lead to unauthorized charges or broken escrow handling if copied into production.

Install only as reference material, not as production-ready payment code. Before adapting it, require explicit charge approval or pre-authorized spending limits, derive identities from authenticated tokens rather than headers, verify webhook signatures before parsing or acting, add idempotency and replay protection, use sandbox or scoped credentials, and implement confirmed escrow release/reconciliation paths.

SkillSpector

By NVIDIA

Vulnerability Patterns

• MCP Tool Poisoning: Hidden Instructions, Unicode Deception, Parameter Description Injection
• Prompt Injection: Instruction Override, Hidden Instructions, Exfiltration Commands
• Data Exfiltration: External Transmission, Env Variable Harvesting, File System Enumeration
• Privilege Escalation: Excessive Permissions, Sudo/Root Execution, Credential Access
• Supply Chain: Unpinned Dependencies, External Script Fetching, Obfuscated Code

Findings (2)

Intent-Code Divergence

High

• Confidence: 97% confidence
• Finding: The method claims to release escrow after fulfillment, but the implementation only notifies the ACP registry and emits an event. This mismatch can leave funds locked indefinitely or cause operators to assume buyer-protected settlement completed when no escrow release actually happened, creating financial and operational risk.

Missing User Warnings

Medium

• Confidence: 84% confidence
• Finding: The text normalizes the idea that simpler MCP clients may let charges settle in the background, which can lead to unauthorized or insufficiently consented payments. In a payments-focused skill, encouraging implicit charging without explicit confirmation materially increases the risk of abuse, mistaken billing, and disputes.

VirusTotal

66/66 vendors flagged this skill as clean.