kinance/circle-agent-stack-mcp

MCP server for Circle's Agent Stack. Create wallets, set spend policies, send USDC, and pay x402-priced endpoints — all from a tool call.
Tools
| Tool | What it does |
|---|---|
| circle_wallet_create | Create an agent wallet (dev/hosted/smart) |
| circle_wallet_list | List wallets with USDC balances |
| circle_balance | Balance + last 10 txns for a wallet |
| circle_policy_set | Set daily cap, x402 cap, allow/block lists |
| circle_transfer_usdc | Send USDC to an on-chain address |
| circle_x402_pay | Pay an x402-priced endpoint and return its response |
Quickstart
You need the Circle CLI installed and authenticated:
Claude Desktop
Claude Code
Example
Self-hosting with x402 paywall
http-server.ts wraps the same tools behind an x402 paywall — agents pay per call in USDC rather than using an API key. Useful if you want to expose Circle tooling as a paid service.
To test the x402 flow locally, run the toy demo server in examples/x402-demo-server.mjs.
How it works
v0.1 shells out to the Circle CLI for all operations. This keeps auth handling out of this repo and avoids reimplementing the API client before the tool surface is validated. v0.2 will switch to direct HTTP via @circle-fin/circle-sdk.
Security
Your Circle API key has spend authority. Always:
- Set daily_cap_usdc before enabling automated payments
- Start on type="dev" wallets, not mainnet
- Review the allowlist before moving to production
- Don't commit CIRCLE_API_KEY
Roadmap
- [ ] circle_nanopayment_stream — streaming x402 payments for per-token billing
- [ ] circle_skills_list / circle_skills_call — Circle Skills marketplace
- [ ] Direct HTTP API mode (v0.2) — remove CLI dependency
- [ ] Multi-chain — EURC, CCTP cross-chain transfers
Related
- Circle Agent Stack docs
- x402 protocol