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 ARC --type agent --output json

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

# Check current Gateway balance (per chain)
circle gateway balance --address <addr> --chain ARC --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 → Arc. Arc uses USDC as its native gas token (no separate gas asset to hold) and has sub-second finality, so a direct Gateway deposit on Arc settles fast — and an eco deposit from BASE lands on Arc too, so either path ends up on the same chain. Use BASE/Polygon when paying sellers that only accept those chains.

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. ARC (or BASE, MATIC, …)
• --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.

READ references/fiat-on-ramp.md for the circle wallet fund --method fiat --open command, settlement notes, and post-purchase balance verification.

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 ARC --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

Verify with circle wallet balance after the transfer confirms — see the "Verify after transfer" section of references/crypto-transfer-alternatives.md.

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 (Arc, 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 Arc (Gateway domain 26) in ~30-50s for a $0.03 flat fee. The follow-up payment is pay --chain ARC.

Use --method direct only when:

1. The user explicitly asked for direct — e.g. "deposit on BASE without going to Arc", "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 Arc — verify by reading the seller's raw 402 accepts[] (not circle services inspect). Eco lands on Arc, so if the seller can't pay there (e.g. a Polygon-only Gateway seller), the Gateway balance won't be reachable for this payment; deposit directly on a chain the seller accepts instead.
4. The user already has vanilla on a fast chain the seller accepts — direct --chain <fast-chain> is fast only on fast-finality chains (Arc, MATIC, AVAX) and skips the eco fee. (e.g., user has 5 USDC vanilla on Polygon → direct --chain MATIC; or vanilla on Arc → direct --chain ARC.)

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 fast timings above are Arc/MATIC/AVAX only — never quote them 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 → Arc)

READ references/gateway-eco-deposit.md for the circle gateway deposit --method eco command (all of --amount, --address, --chain, --method are required) and Gateway balance verification.

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 Arc. The chain on pay must match where the balance lives.