Circle Agent Stack Mcp

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Summary

Wraps Circle's Agent Stack so Claude can create USDC wallets, set spending policies, transfer funds, and pay x402 endpoints that bill per call in stablecoin. You get six tools: wallet creation and listing, balance checks, policy management, standard USDC transfers, and x402 payments that return the API response along with the amount paid. Currently shells out to the Circle CLI for auth and operations, with direct SDK support planned for v0.2. Worth looking at if you're building agents that need to handle crypto payments autonomously or consume APIs that charge in USDC instead of requiring API keys. Start with dev wallets and set daily caps before you point it at anything live.

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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.

npx circle-agent-stack-mcp

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:

npm install -g @circle-fin/circle-cli
circle login
export CIRCLE_API_KEY=your_key_here

Claude Desktop

{
  "mcpServers": {
    "circle": {
      "command": "npx",
      "args": ["-y", "circle-agent-stack-mcp"],
      "env": {
        "CIRCLE_API_KEY": "your_key_here"
      }
    }
  }
}

Claude Code

claude mcp add circle -- npx -y circle-agent-stack-mcp

Example

You: Create a dev wallet called eva-treasury, set a $5 daily cap and $0.10 x402 cap,
     then fetch today's BTC signal from the x402 endpoint at https://signals.example.co/btc

Claude:
→ circle_wallet_create("eva-treasury", type="dev")
  { wallet_id: "wal_abc123", address: "0x..." }

→ circle_policy_set("wal_abc123", daily_cap_usdc=5, x402_cap_usdc=0.10)
  { status: "applied" }

→ circle_x402_pay("wal_abc123", "https://signals.example.co/btc", max_price_usdc=0.10)
  { signal: "LONG", confidence: 0.72, price_paid_usdc: 0.05 }

Today's BTC signal: LONG (72% confidence). Paid $0.05.

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.

CIRCLE_PAYOUT_ADDRESS=0x... npm run start:http

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

Featured

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Connect Mailtrap MCP →

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Install now →

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Make coding agent sessions - Searchable, Shareable, Vendor-neutral & Scored.

Try For Free →

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Your agent targets a perfect 10 Code Health score. Deterministic. Every commit.

Try For Free →

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Integrate web data into your AI product. One API to scrape website & brand data.

Get API Key Now →

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one prompt install →

Configuration

CIRCLE_API_KEY*secret

Your Circle API key from developers.circle.com

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.

npx circle-agent-stack-mcp

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:

npm install -g @circle-fin/circle-cli
circle login
export CIRCLE_API_KEY=your_key_here

Claude Desktop

{
  "mcpServers": {
    "circle": {
      "command": "npx",
      "args": ["-y", "circle-agent-stack-mcp"],
      "env": {
        "CIRCLE_API_KEY": "your_key_here"
      }
    }
  }
}

Claude Code

claude mcp add circle -- npx -y circle-agent-stack-mcp

Example

You: Create a dev wallet called eva-treasury, set a $5 daily cap and $0.10 x402 cap,
     then fetch today's BTC signal from the x402 endpoint at https://signals.example.co/btc

Claude:
→ circle_wallet_create("eva-treasury", type="dev")
  { wallet_id: "wal_abc123", address: "0x..." }

→ circle_policy_set("wal_abc123", daily_cap_usdc=5, x402_cap_usdc=0.10)
  { status: "applied" }

→ circle_x402_pay("wal_abc123", "https://signals.example.co/btc", max_price_usdc=0.10)
  { signal: "LONG", confidence: 0.72, price_paid_usdc: 0.05 }

Today's BTC signal: LONG (72% confidence). Paid $0.05.

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.

CIRCLE_PAYOUT_ADDRESS=0x... npm run start:http

To test the x402 flow locally, run the toy demo server in examples/x402-demo-server.mjs.

How it works

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

Circle Agent Stack Mcp

circle-agent-stack-mcp

Tools

Quickstart

Claude Desktop

Claude Code

Example

Self-hosting with x402 paywall

How it works

Security

Roadmap

Related

Configuration

Circle Agent Stack Mcp

circle-agent-stack-mcp

Tools

Quickstart

Claude Desktop

Claude Code

Example

Self-hosting with x402 paywall

How it works

Security

Roadmap

Related

Configuration

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