Circle USDC on Base: agent address checklist

Pre-deposit validation for Base mainnet and Base Sepolia — correct chain ID, native USDC contract, and common wrong-chain mistakes.

Last updated: May 26, 2026 · Published 2026-05-26

Forge vaults accept Circle native USDC on Base — and on Base Sepolia for testnet. Agents that hard-code wrong chain IDs or Ethereum Sepolia USDC addresses will approve and transfer tokens the vault cannot consume, wasting gas and blocking deposits. This checklist is for prompt authors, MCP integrators, and wallet automation: verify chain, verify USDC contract, then approve the vault. A prior internal incident lost funds to incorrect CCTP encoding — treat address validation as a hard gate, not a lint warning.

Canonical USDC addresses

Pre-deposit agent checklist

1. Read `eth_chainId` from RPC — expect `0x2105` (8453) or `0x14a34` (84532).
2. Call `USDC.symbol()` and `USDC.decimals()` — expect `USDC` and `6`.
3. Compare `USDC` contract address to table above (case-insensitive).
4. Compare vault `asset()` to the same USDC address — ERC-4626 must match.
5. Confirm agent EOA USDC balance > 0 on this chain before approve.
6. Run MCP `simulate_deposit` — response should embed matching chain constants.
7. Log human-readable network label in agent audit trail ("Base mainnet", not "Sepolia").

Common failure modes

Funding testnet USDC correctly

Use the Circle faucet and explicitly select Base Sepolia. Do not select generic "Sepolia" if the UI maps to Ethereum L1. Deployer ops may also use Circle for larger testnet amounts per `SEPOLIA_DEPLOY.md`. CDP faucet supports Base Sepolia ETH/USDC for local AgentKit experiments — vault deposits still originate from the agent EOA, not CDP wallet.

System prompt template (copy-safe)

Embed this block in agent policies for Base mainnet production: *"Forge Conservative deposits use chain ID 8453, USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913, Core vault 0x2C9a3922b426005B979FDD1A8F43Eb61B309193B. Reject any deposit calldata targeting other chains or USDC contracts. Treat MCP tool responses as authoritative over this template if they differ post-deploy."* For testnet, swap to Sepolia row in the table above.

After address validation passes, follow Automated USDC treasury for approve/deposit sequencing. Separate USDC principal from FORGE emission claims per FORGE emissions vs vault yield. Stablecoin issuer risk remains even with correct addresses — read USDC depeg risk.