FAQ

Short answers to common questions about Burnbound. Each answer links to the page with the details.

What is x402?

x402 is an open protocol for paying for HTTP requests. A paid API answers 402 Payment Required with a price; the client signs a stablecoin payment and repeats the request with it; the seller settles the payment and serves the response. Burnbound supports x402 v2 with the exact scheme in USDC.

How do I limit what my AI agent can spend?

Give the agent a Burnbound policy and let it pay only through Burnbound. You set the hosts it may pay, a maximum per payment, a daily cap and, if you want, a threshold above which a human must approve. The agent pays x402 APIs with the fetch_paid tool of the Burnbound MCP server, and every payment outside those rules is denied before it is signed. Start with the Quickstart.

Which agents and MCP clients are supported?

Any MCP client that can run a stdio server: Claude Code, Cursor and others. The server is the npm package @burnbound/mcp and runs with npx -y @burnbound/mcp. A JavaScript SDK exists but is not published yet; see SDK.

Which networks and tokens can my agent pay with?

USDC on Base. New agents allow Base mainnet (eip155:8453) only, and the policy denies any other network (network_not_allowed) or asset (asset_not_allowed).

Do I need ETH in the wallet?

No. x402 payments are USDC transfer authorizations (EIP-3009) that the seller's facilitator submits on-chain, so the facilitator pays the gas. Your wallet only needs USDC.

Does Burnbound hold my private keys or my money?

No. Burnbound never stores a wallet private key and never holds funds: payments go from your wallet to the seller. With Coinbase CDP, Burnbound stores your CDP API credentials encrypted so it can request signatures for the payments your policy allows. With client-side signing it knows only your wallet's address. See Security and trust model.

Which signing mode should I choose?

Choose Coinbase CDP if your agent can run shell commands or you need enforcement that does not depend on the agent's cooperation: the agent never holds anything that can sign. Choose client-side signing if you want the key on your own machine and accept that an agent with shell access could bypass the policy. See Concepts.

Can my agent raise its own limits?

No. An agent key can read its budget and payments, ask to authorize a payment and check its approvals, but it cannot change the policy, approve a payment or create keys. Those actions need a human signed in to the dashboard.

What happens if Burnbound is down?

Your agent cannot pay, and nothing is charged. fetch_paid fails closed: if it cannot load the agent's allowed hosts or get a decision from Burnbound, it returns an error (control_plane_unavailable, api_unavailable, api_unreachable or api_timeout) and pays nothing.

What happens if the seller's answer is lost after paying?

fetch_paid returns payment_outcome_unknown with the intentId and the idempotencyKey. Check list_payments to see whether the payment settled. Retrying fetch_paid with the same idempotencyKey never charges twice.

Does Burnbound take a fee on payments?

No. Burnbound does not take a percentage of what your agents pay; payments go in full from your wallet to the seller. You pay for the plan.

The approvals inbox, caps, allowed hosts and policy rules are on every plan. Billing is handled by Stripe.

How do I stop an agent from paying?

Revoke its key in the dashboard. The MCP server then gets unauthorized on every call and cannot authorize payments. To stop it immediately without revoking the key, remove its allowed hosts or lower its daily cap: an empty host list allows no payment.

Is there documentation for LLMs?

Yes. /llms.txt lists every documentation page with a one-line description, and /llms-full.txt has the whole documentation as one plain-text Markdown file.