EVM DEX Swap (Uniswap V3)

Swap tokens on-chain via Uniswap V3 exactInputSingle using the caw CLI.

This skill depends on cobo-agentic-wallet for wallet operations. The wallet must be onboarded (caw onboard complete) and hold sufficient token balance before executing swaps.

Chain selection

Match the user's requested chain to the configuration below. If the user doesn't specify a chain, ask which one they want.

Network	Chain ID	Router	WETH	USDC	Default Fee
Sepolia	SETH	0x3bFA4769FB09eefC5a80d6E87c3B9C650f7Ae48E	0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14	0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238	3000
Ethereum	ETH	0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45	0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2	0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48	500
Base	BASE	0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45	0x4200000000000000000000000000000000000006	0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913	500
Arbitrum	ARBITRUM	0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45	0x82aF49447D8a07e3bd95BD0d56f35241523fBab1	0xaf88d065e77c8cC2239327C5EDb3A432268e5831	500

Fee tiers: 100 (0.01% stable pairs), 500 (0.05% blue-chip), 3000 (0.3% standard), 10000 (1% exotic). Use the fee tier matching the deployed pool — sending to a non-existent pool reverts.

Workflow

1. Pre-flight checks

Before swapping, verify the wallet state:

# Check balance — confirm the input token is available
caw --format json wallet balance

# If user holds native ETH but needs WETH, wrap it first — see references/weth-wrapping.md

If the wallet holds native ETH instead of WETH, read references/weth-wrapping.md for the wrapping procedure before continuing.

2. Set variables

Look up the correct values from the chain table above and set them before running any commands:

WALLET_ADDR="<wallet_addr>"   # from `caw --format json address list`
CHAIN="<chain_id>"            # e.g. ETH, BASE, ARBITRUM, SETH
ROUTER="<router_address>"    # from chain table
TOKEN_IN="<token_in_address>" # e.g. WETH address
TOKEN_OUT="<token_out_address>" # e.g. USDC address
FEE="<fee_tier>"              # e.g. 500
AMOUNT_IN="<amount_in_wei>"   # token amount in smallest unit
AMOUNT_OUT_MIN="<min_out>"    # slippage protection — see notes

3. Approve token (one-time per token)

The Uniswap Router needs ERC-20 approval to spend the input token. This only needs to happen once per token.

APPROVE_CALLDATA=$(caw util abi encode \
  --method "approve(address,uint256)" \
  --args "[\"$ROUTER\", \"115792089237316195423570985008687907853269984665640564039457584007913129639935\"]")

caw --format json tx call \
  --contract "$TOKEN_IN" \
  --calldata "$APPROVE_CALLDATA" \
  --chain "$CHAIN" \
  --src-addr "$WALLET_ADDR"

4. Execute swap

SWAP_CALLDATA=$(caw util abi encode \
  --method "exactInputSingle((address,address,uint24,address,uint256,uint256,uint160))" \
  --args "[\"$TOKEN_IN\", \"$TOKEN_OUT\", \"$FEE\", \"$WALLET_ADDR\", \"$AMOUNT_IN\", \"$AMOUNT_OUT_MIN\", \"0\"]")

caw --format json tx call \
  --contract "$ROUTER" \
  --calldata "$SWAP_CALLDATA" \
  --chain "$CHAIN" \
  --src-addr "$WALLET_ADDR"

# Check transaction status
caw --format json tx get <tx_id>

Example — swap 0.01 WETH → USDC on Ethereum:

CHAIN="ETH"
ROUTER="0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45"
WETH="0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2"
USDC="0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"

# Approve WETH (one-time)
APPROVE=$(caw util abi encode --method "approve(address,uint256)" --args "[\"$ROUTER\", \"115792089237316195423570985008687907853269984665640564039457584007913129639935\"]")
caw --format json tx call --contract "$WETH" --calldata "$APPROVE" --chain "$CHAIN" --src-addr "$WALLET_ADDR"

# Swap 0.01 WETH (10000000000000000 wei) → USDC
# NOTE: amount_out_min is "0" here for demo only — on mainnet with real value, always set a non-zero minimum
SWAP=$(caw util abi encode --method "exactInputSingle((address,address,uint24,address,uint256,uint256,uint160))" --args "[\"$WETH\", \"$USDC\", \"500\", \"$WALLET_ADDR\", \"10000000000000000\", \"0\", \"0\"]")
caw --format json tx call --contract "$ROUTER" --calldata "$SWAP" --chain "$CHAIN" --src-addr "$WALLET_ADDR"

Important notes

• Slippage protection: On mainnet, set amount_out_min to reject unfavorable fills (e.g. expected_amount * 0.995 for 0.5% slippage). Never use 0 on mainnet for real value.
• --format json: Use on all caw commands for parseable output.
• Status lifecycle: Submitted → PendingScreening → Broadcasting → Confirming → Completed
• Gas: Cobo Gasless sponsors gas by default. On L2 (Arbitrum, Optimism), gas costs are much lower.
• Error handling: If a swap is denied by policy, check the suggestion field in the error — see the parent skill's error-handling.

Reference

Topic	Read
WETH wrapping (native ETH → WETH)	references/weth-wrapping.md
Complete buy+sell swap cycle script	references/swap-cycle.md