💳fund-agent-wallet

Overview

For an overview of the Circle CLI's full capability set — bridging, smart contract execution, x402 payment, and more — see the use-circle-cli master skill. This skill is the narrower funding flow.

Funding an agent wallet means putting USDC where the CLI can spend it. There are two balance pools to be aware of:

• On-chain (vanilla x402) — USDC sitting at the wallet address on a specific chain. Each chain is separate. Used to pay endpoints whose accepts[] does not include GatewayWalletBatched. Settles in one block.
• Nanopayments (powered by Gateway) — USDC held off-chain in your Circle Gateway balance, batched and settled for you across supported chains. Per source chain — no cross-chain pooling at payment time. Used to pay endpoints whose accepts[] includes GatewayWalletBatched. Settles in <500ms once the balance exists.

Gas note

Agent wallet payment flows are gas-abstracted — users can pay with USDC without pre-funding native gas.

This skill covers funding both pools. Pick the path with the shortest time-to-result and hide chain complexity from the user.

Prerequisites

# Confirm session is good
circle wallet status

# Get the wallet address
circle wallet list --chain BASE --type agent --output json

# Check current on-chain balance (per chain)
circle wallet balance --address <addr> --chain BASE --output json

# Check current Gateway balance (per chain)
circle gateway balance --address <addr> --chain BASE --output json

If circle wallet status errors with "Not logged in" or "Terms acceptance is required", hand off to the use-agent-wallet skill — it covers install, terms, login, and wallet creation.

Step 1 — Pick a funding path

Ask the user: "How would you like to fund your wallet?"

• Fiat (USD or local currency) — Buy USDC with a card or bank transfer via the CLI's built-in fiat on-ramp. Best for users who don't have crypto yet.
• Existing USDC — Send USDC from a wallet they already have (MetaMask, Coinbase, Phantom, etc.). Faster and free of on-ramp fees.
• Gateway deposit (advanced) — Move existing on-chain USDC into the Gateway balance for low-latency batched payments. Only useful if the seller they're paying supports Gateway on a specific chain.

Default recommendation: existing USDC → BASE. Fastest, lowest friction, and BASE is the most commonly accepted chain across the marketplace.

Step 2 — Required flags for non-interactive use

The CLI prompts for missing values when run interactively. Agents are non-interactive, so every circle wallet fund invocation against mainnet MUST include:

• --address <addr> — wallet address from circle wallet list
• --chain <chain> — e.g. BASE
• --method <fiat|crypto> — without it: Error: --method is required in non-interactive mode.
• --amount <number> — USDC amount; without it: Error: --amount is required.

--token usdc is the default and can be omitted, but pass it explicitly when the user asked for USDC specifically.

Path A — Fiat on-ramp

Opens a fiat on-ramp window in the user's default browser. Funds deposit directly to the wallet on the selected chain.

circle wallet fund --address <addr> --chain BASE --amount 25 --token usdc --method fiat --open

The user completes purchase in the on-ramp window. USDC arrives in the wallet on the selected chain after on-ramp settlement (typically minutes for card, longer for bank transfer).

Verify after the user reports purchase complete:

circle wallet balance --address <addr> --chain BASE --output json

Path B — Crypto transfer (existing USDC)

The user already holds USDC somewhere (another wallet, an exchange, etc.) and wants to send it to the agent wallet.

Recommended — browser-rendered QR (best UX)

circle wallet fund --address <addr> --chain BASE --amount 10 --token usdc --method crypto --open

--open renders the EIP-681 QR code on a local HTML page in the user's default browser. Use this by default. Terminal-rendered QR codes are frequently truncated or unscannable inside agent UIs (Claude Code, Codex, etc.); the browser page renders the QR at full resolution and works on both desktop and mobile.

The user scans the QR with any mobile wallet (MetaMask, Coinbase Wallet, Rainbow, Phantom) and confirms the transfer.

Alternatives — PNG export or manual transfer

If the user can't scan a browser QR, READ references/crypto-transfer-alternatives.md (QR-to-PNG via --export, manual transfer details including USDC contract addresses).

Verify after transfer

circle wallet balance --address <addr> --chain BASE --output json

Path C — Gateway deposit (powered by Gateway, advanced)

Only suggest a Gateway deposit when:

• The user has on-chain USDC, AND
• They want to pay a service whose accepts[] includes GatewayWalletBatched on a specific chain, AND
• That chain is one Gateway supports (Polygon, BASE, ETH, ARB, OP, AVAX, UNI).

Eco vs direct — pick eco unless one of four conditions holds

circle gateway deposit --method eco deposits BASE vanilla USDC into Gateway and lands on Polygon (Gateway domain 7) in ~30-50s for a $0.03 flat fee. The follow-up payment is pay --chain MATIC.

Use --method direct only when:

1. The user explicitly asked for direct — e.g. "deposit on BASE without going to Polygon", "stay on BASE", "use direct deposit". Implicit preferences and your own inferences do not count.
2. The source chain isn't supported by eco — eco only supports BASE as a source today; check circle gateway deposit --help for the current list. Trying an unsupported source returns "Unknown method" or chain-not-supported.
3. The seller does NOT accept Gateway on Polygon — verify by reading the seller's raw 402 accepts[] (not circle services inspect). Eco lands on Polygon, so if the seller can't pay there, the Gateway balance won't be reachable for this payment.
4. The user already has vanilla on a fast chain the seller accepts — direct --chain <fast-chain> is ~8s on the fast chains only (MATIC, AVAX) and skips the eco fee. (e.g., user has 5 USDC vanilla on Polygon → direct --chain MATIC.)

If none of conditions 1–4 holds, the answer is eco. Picking direct anyway is slow on BASE: direct on BASE (and ETH/ARB/OP/UNI) waits ~13–19 minutes for finality + gas, vs eco's ~30-50s + $0.03. (The ~8s above is MATIC/AVAX only — never quote it for BASE.)

Compare per-workflow, not per-call

Eco's cold-start (~30-50s + $0.03) is paid once; every Gateway call after is <500ms. Vanilla has no deposit but every call costs ~2s forever with no amortization. Agentic workflows are rarely single-call, so treat the deposit as one-time wallet onboarding, not a per-call cost. (Time breakeven is ~N=7-13 calls, but Gateway-only seller access and <500ms future calls already win at call 1.)

Eco deposit (BASE → Polygon)

# Deposit (--amount, --address, --chain, --method are all required)
circle gateway deposit --amount 10 --address <addr> --chain BASE --method eco

# Verify (Gateway balance shows Polygon in the per-chain breakdown)
circle gateway balance --address <addr> --chain BASE --output json
# First payment/transfer on a new chain auto-deploys the wallet (see Troubleshooting).

Once the deposit verifies, hand off to the pay-via-agent-wallet skill for the actual payment — that skill owns the circle services pay flow (including its allowed-tools whitelist and gotchas).

Common mistake: using --chain BASE on the pay call when the Gateway balance landed on Polygon. The chain on pay must match where the balance lives.

Direct deposit and Gateway withdrawals

When a condition for --method direct holds (above), or the user wants USDC back out of Gateway, READ references/gateway-direct-and-withdraw.md — direct command syntax, supported chains and timings, and the same-chain-only withdraw + circle bridge transfer pattern.

Troubleshooting

On ANY funding error (missing flags, unscannable QR, Wallet not deployed, Insufficient balance, wrong chain after eco, withdraw limits), READ references/troubleshooting.md for the error table and reference links.

Rules

• NEVER prompt users to send USDC to addresses you generated. ALWAYS use the user's own wallet from circle wallet list.
• NEVER store, log, or display private keys.
• ALWAYS pass --method <fiat|crypto> to circle wallet fund — agents are non-interactive and the CLI will not prompt.
• ALWAYS pass --amount <number> to circle wallet fund — confirm the amount with the user first.
• ALWAYS prefer --method crypto --open over rendering QR codes in the terminal — terminal QR codes get truncated inside Claude Code, Codex, and similar agent UIs and become unscannable.
• For fiat: use --method fiat --open so the on-ramp loads in the browser.
• NEVER suggest a Gateway eco deposit unless you have verified the target service supports Gateway on Polygon via the discovery API or the seller's raw 402 accepts[].
• NEVER deposit 100% of the user's vanilla balance into Gateway. The wallet needs vanilla headroom for vanilla-only sellers the user may hit next.
• Sizing formula: amount = max(price × N + fee + slack, Gateway minimum), where N is the workflow's expected call count. Typically reserve ~50% of vanilla as a soft headroom floor. Gateway enforces a server-side minimum deposit; sizing below it returns an error, so floor your suggestion to that minimum. Run circle gateway deposit --help for current bounds.
• Surface to the user before depositing when the required amount is materially larger than the workflow's total cost (cheap-endpoint case: $0.0024/call × 5 = $0.012, but the Gateway minimum sets the floor) or above the user's stated --max-amount cap. Don't silently deposit ~100× the task cost.
• The first real transaction on a new chain deploys the SCA — there is no dedicated "deploy" command today. Consult circle wallet --help for the current options if a Wallet not deployed error appears.
• ALWAYS use --chain matching where the balance lives. Eco lands on Polygon → pay --chain MATIC. Direct lands on the source chain → pay --chain <same>.
• Gateway does NOT do cross-chain transfers at payment time. Source chain matters.
• Abstract chain details from the user unless they explicitly want technical specifics. The user asked to fund the wallet; they don't need a tour of EVM finality.
• If the circle CLI itself causes friction during funding (unexpected error, confusing output, missing capability), file feedback per the use-circle-cli skill's Report friction (feedback) section.

Alternatives

Trigger the use-agent-wallet skill instead when:

• The user has not yet logged in to the CLI or accepted Terms.
• circle wallet status errors with "Not logged in" or "Terms acceptance is required".
• The user is asking about wallet setup, login, or session state — not funding.

Trigger the pay-via-agent-wallet skill instead when:

• The user wants to call or pay for a paid x402 service.
• Funding has completed and the user is ready to use the marketplace.
• The user mentions circle services pay, circle services search, or any "pay for" prompt.

Trigger the agent-wallet-policy skill instead when:

• The user wants to set spending limits before funding (rare — most users fund first, set limits later).
• The user mentions per-tx / daily / weekly / monthly caps, spending policy, or wallet rules.

For cross-chain USDC moves the agent should use circle bridge transfer directly — it is part of the Circle CLI (see references/gateway-direct-and-withdraw.md for the withdraw-then-bridge pattern).

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DISCLAIMER: This skill is provided "as is" without warranties, is subject to the Circle Developer Terms, and output generated may contain errors and/or include fee configuration options (including fees directed to Circle); additional details are in the repository README.