x402-mcp-server
Provides an MCP server that implements an x402-style micropayment gateway for AI agents. It exposes MCP tools to create payment requests, verify USDC payments on Solana, query payment status/history, set per-tool pricing, and fetch revenue statistics.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
The README describes configuration via environment variables (MERCHANT_WALLET, SOLANA_RPC_URL) which is generally safer than hardcoding secrets. However, there is no documented authentication/authorization for who can call the MCP tools, and no mention of protecting merchant keys or handling sensitive data. Dependency hygiene is not verifiable from provided content; only a short dependency list is shown.
⚡ Reliability
Best When
You want agent-to-agent paywalling for specific tools using on-chain USDC verification and are comfortable validating correctness/security in your own environment.
Avoid When
You need clearly documented API contracts, guaranteed idempotency, or documented error/retry behavior for financial workflows.
Use Cases
- • Charging other agents for premium tool calls via USDC micropayments on Solana
- • Gating access to paid functionality between autonomous agents
- • Tracking revenue and audit history for tool usage priced per call
Not For
- • General-purpose payment processing for end-user commerce
- • Use cases requiring formal compliance guarantees or enterprise-grade operational guarantees (not evidenced here)
- • Production deployments where robust operational docs (SLA, retries, idempotency semantics) must be proven
Interface
Authentication
No user-facing authentication mechanism is described; the server appears configured with a merchant wallet and connects to a Solana RPC endpoint. Authorization/authz for who can invoke tools is not described in the provided README.
Pricing
Project is open-source (MIT per manifest/README). Financial costs are blockchain fees and any USDC transfer costs.
Agent Metadata
Known Gotchas
- ⚠ No idempotency/retry guidance documented for payment creation/verification—agents may duplicate requests if they retry aggressively.
- ⚠ No explicit tool input/output schema or error code semantics provided in the README excerpt, making robust agent handling harder.
- ⚠ On-chain verification requires correct USDC/memo/payment parameters; incorrect setup could lead to false negatives/positives (not documented).
Alternatives
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Scores are editorial opinions as of 2026-04-04.