swap-build

name	swap-build
description	This skill should be used when the user asks to "swap-build", "build a swap transaction", "build swap calldata", "create swap tx", "swap tokens", "trade crypto", "execute a token exchange", "swap ETH to USDC", "convert tokens", or needs encoded calldata for on-chain submission. Fetches the best route and builds transaction data via KyberSwap Aggregator.
metadata	{"tags":["defi","kyberswap","swap","transaction","evm","aggregator"],"provider":"KyberSwap","homepage":"https://kyberswap.com"}

KyberSwap Build Skill

Build swap transactions using the KyberSwap Aggregator. Given a token pair, amount, and sender address, fetch the best route and generate encoded calldata ready for on-chain submission.

This is a three-step process:

1. GET the optimal route (same as the quote skill)
2. Show quote details and ask for user confirmation
3. POST to build the encoded transaction calldata

Input Parsing

The user will provide input like:

• 100 USDC to ETH on arbitrum from 0xAbc123...
• 1 ETH to USDC on ethereum from 0xAbc123... slippage 100
• 0.5 WBTC to DAI on polygon from 0xAbc123... to 0xDef456...

Extract these fields:

• amount — the human-readable amount to swap
• tokenIn — the input token symbol
• tokenOut — the output token symbol
• chain — the chain slug (default: ethereum)
• sender — the address that will send the transaction (required)
• recipient — the address to receive output tokens (default: same as sender). WARNING: When the recipient address differs from the sender, display a prominent warning: "Output tokens will be sent to a DIFFERENT address than the sender. Please verify the recipient address carefully."
• slippageTolerance — slippage in basis points (see Slippage Defaults below)

If the sender address is not provided, ask the user for it before proceeding. Do not guess or use a placeholder address.

Sender address validation — reject or warn before proceeding:

• Must not be the zero address (0x0000000000000000000000000000000000000000) — this is an invalid sender and the transaction will fail.
• Must not be the native token sentinel (0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE) — this is a placeholder for native tokens, not a real account.
• Warn if it matches a known contract address (e.g., a token address or the router address) — sending from a contract address is unusual and likely a mistake. Ask the user to confirm.

Slippage Defaults

If the user does not specify slippage, choose based on the token pair:

Pair type	Default	Rationale
Stablecoin ↔ Stablecoin (e.g. USDC→USDT)	5 bps (0.05%)	Minimal price deviation between pegged assets
Common tokens (e.g. ETH→USDC, WBTC→ETH)	50 bps (0.50%)	Standard volatility buffer
All other / unknown pairs	100 bps (1.00%)	Conservative default for long-tail or volatile tokens

These are recommended defaults, not official KyberSwap values. The KyberSwap API defaults to slippageTolerance: 0 if omitted.

Note: The API defaults to 0 if slippageTolerance is omitted. Always pass an explicit value. The range is [0, 2000] (0% to 20%). Use ignoreCappedSlippage: true to exceed 20%.

Workflow

Step 1: Resolve Token Addresses

Read the token registry at ${CLAUDE_PLUGIN_ROOT}/references/token-registry.md.

Look up tokenIn and tokenOut for the specified chain. Match case-insensitively. Note the decimals for each token.

Aliases to handle:

• "ETH" on Ethereum/Arbitrum/Optimism/Base/Linea/Unichain → native token address
• "MATIC" or "POL" on Polygon → native token address
• "BNB" on BSC → native token address
• "AVAX" on Avalanche → native token address
• "MNT" on Mantle → native token address
• "S" on Sonic → native token address
• "BERA" on Berachain → native token address
• "RON" on Ronin → native token address
• "XTZ" on Etherlink → native token address
• "MON" on Monad → native token address

If a token is not found in the registry: Use the fallback sequence described at the bottom of ${CLAUDE_PLUGIN_ROOT}/references/token-registry.md:

1. KyberSwap Token API (preferred) — search whitelisted tokens first: https://token-api.kyberswap.com/api/v1/public/tokens?chainIds={chainId}&name={symbol}&isWhitelisted=true via WebFetch. Pick the result whose symbol matches exactly with the highest marketCap. If no whitelisted match, retry without isWhitelisted (only trust verified or market-cap tokens). If still nothing, browse page=1&pageSize=100 (try up to 3 pages).
2. CoinGecko API (secondary fallback) — search CoinGecko for verified contract addresses if the Token API doesn't have it.
3. Ask user manually (final fallback) — if CoinGecko also fails, ask the user to provide the contract address. Never guess or fabricate addresses.

Step 2: Check Token Safety

For any token not in the built-in registry and not a native token, check the honeypot/FOT API:

GET https://token-api.kyberswap.com/api/v1/public/tokens/honeypot-fot-info?chainId={chainId}&address={tokenAddress}

Via WebFetch, check both tokenIn and tokenOut:

• If isHoneypot: true — refuse the swap and warn the user that this token is flagged as a honeypot (cannot be sold after buying).
• If isFOT: true — warn the user that this token has a fee-on-transfer (tax: {tax}%). The actual received amount will be less than the swap output. Proceed only if the user acknowledges the tax.

Step 3: Convert Amount to Wei

amountInWei = amount * 10^(tokenIn decimals)

The result must be a plain integer string with no decimals, no scientific notation, and no separators.

Step 4: Get the Route (GET request)

Read the API reference at ${CLAUDE_PLUGIN_ROOT}/references/api-reference.md for the full specification.

Make the request using WebFetch:

URL: https://aggregator-api.kyberswap.com/{chain}/api/v1/routes?tokenIn={tokenInAddress}&tokenOut={tokenOutAddress}&amountIn={amountInWei}&source=ai-agent-skills&origin={sender}
Prompt: Return the full JSON response body exactly as received. I need the complete routeSummary object.

If the route request fails, check the code field in the JSON response:

Code	Message	Quick Fix
4008	Route not found	No liquidity for this pair/amount. Remove source filters, try a smaller amount, or retry.
4011	Token not found	Verify the token address is correct for this chain. Use 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE for native tokens.
4000	Bad request	Read fieldViolations in the response. amountIn must be a plain integer string in wei. Addresses must be 42-char hex with lowercase 0x.
4010 / 40011	No eligible pools / Filtered sources (observed behavior, not in public API docs)	Remove includedSources/excludedSources filters.
404	Chain not found	Check chain slug spelling: ethereum, bsc, polygon, arbitrum, optimism, avalanche, base, linea, mantle, sonic, berachain, ronin, unichain, hyperevm, plasma, etherlink, monad, megaeth.

For any error not listed here, refer to ${CLAUDE_PLUGIN_ROOT}/skills/error-handling/SKILL.md.

Extract the data.routeSummary object from the response. You need the complete routeSummary object for the build step.

Step 4a: Dust Amount Check

After getting a successful route, check the USD values from the routeSummary:

• If amountInUsd < $0.10 — warn the user and ask for confirmation: "This swap amount is extremely small ($X). Gas fees ($Y) will far exceed the swap value. Do you still want to proceed?"
• If gasUsd > amountInUsd — warn the user and ask for confirmation: "Gas cost ($Y) exceeds the swap value ($X). This trade is uneconomical. Do you still want to proceed?"

If the user declines, abort the swap. Do NOT proceed to the build step.

Step 4b: Display Quote and Request Confirmation

CRITICAL: Always show quote details and ask for confirmation before building the transaction.

Calculate the output amount and rate from the routeSummary:

amountOut = routeSummary.amountOut / 10^(tokenOut decimals)
rate = amountOut / amount
minAmountOut = amountOut * (1 - slippageTolerance/10000)

Present the quote details:

## Swap Quote — Confirmation Required

**{amount} {tokenIn} → {amountOut} {tokenOut}** on {Chain}

| Detail | Value |
|---|---|
| You send | {amount} {tokenIn} (~${amountInUsd}) |
| You receive | {amountOut} {tokenOut} (~${amountOutUsd}) |
| Exchange rate | 1 {tokenIn} = {rate} {tokenOut} |
| Minimum received | {minAmountOut} {tokenOut} (after {slippage}% slippage) |
| Price impact | {priceImpact}% *(from routeSummary.extraFee.feeAmount if available)* |
| Gas estimate | {gas} units (~${gasUsd}) |
| Route | {routeSummary.route description — e.g., "Uniswap V3 → Curve"} |

### Addresses

| Field | Value |
|---|---|
| Router | `{routerAddress}` |
| Sender | `{sender}` |
| Recipient | `{recipient}` |

---

⚠️ **Review the quote carefully:**
- Verify the exchange rate is acceptable
- Check the minimum received amount
- Ensure the router address is correct (`0x6131B5fae19EA4f9D964eAc0408E4408b66337b5` on most chains)

**Do you want to proceed with building this swap transaction?** (yes/no)

Wait for the user to explicitly confirm with "yes", "confirm", "proceed", or similar affirmative response before building the transaction.

If the user says "no", "cancel", or similar, abort and inform them the swap was cancelled. Do NOT proceed to Step 5.

Note: Routes expire quickly (~30 seconds). If the user takes too long to confirm, warn them that the quote may be stale and offer to re-fetch.

Step 5: Build the Transaction (POST request)

Only proceed to this step after the user confirms in Step 4b.

WebFetch only supports GET requests, so use Bash(curl) for this POST request.

Construct the curl command:

curl -s -X POST "https://aggregator-api.kyberswap.com/{chain}/api/v1/route/build" \
  -H "Content-Type: application/json" \
  -H "X-Client-Id: ai-agent-skills" \
  -d '{
    "routeSummary": {PASTE THE COMPLETE routeSummary OBJECT HERE},
    "sender": "{sender}",
    "recipient": "{recipient}",
    "origin": "{sender}",
    "slippageTolerance": {slippageTolerance},
    "deadline": {CURRENT_UNIX_TIMESTAMP + 1200},
    "source": "ai-agent-skills"
  }'

To get the current unix timestamp + 20 minutes for the deadline:

echo $(($(date +%s) + 1200))

You can combine this into one command or compute it separately.

Important: The routeSummary field must contain the exact JSON object returned from Step 4. Do not modify, truncate, or reformat it.

Optional fields (include if relevant):

• Add "permit": "{encoded_permit}" if the user provides an ERC-2612 permit signature (skips the separate approval tx).
• Add "enableGasEstimation": true for a more accurate gas figure.
• Add "ignoreCappedSlippage": true if the user requests slippage above 20%.

See ${CLAUDE_PLUGIN_ROOT}/references/api-reference.md for all available fields.

Step 5b: Handle Build Errors

If the build request fails, check the code field in the JSON response:

Code	Message	Quick Fix
4227	return amount is not enough	Price moved since route fetch. Fetch a fresh route and retry (recommended). The response includes suggestedSlippage (in bps) as a fallback.
4227	insufficient funds for gas * price + value	Sender doesn't have enough native token (ETH/MATIC/etc.) to cover amountIn + gas. Reduce amount or top up wallet.
4227	TRANSFER_FROM_FAILED	Sender hasn't approved the router to spend the input token, or token balance is insufficient. Check approval and balance.
4222	Quoted amount smaller than estimated	RFQ/limit order quote came in lower than estimated. Fetch a fresh route and retry. Or use excludeRFQSources: true to avoid RFQ sources.
4002	Request body malformed	Ensure deadline and slippageTolerance are numbers, booleans are true/false. Do NOT modify the routeSummary object.
40010 (observed behavior, not in public API docs)	Empty sender address	Provide a valid sender address, or set enableGasEstimation: false.
4000	Bad request	Read fieldViolations. Common: slippageTolerance > 2000 needs ignoreCappedSlippage: true, deadline must be in the future, recipient is required.
PMM/RFQ errors	Various maker errors	Fetch a fresh route and retry. Or use excludedSources to skip the failing maker. See the table below.

Common PMM/RFQ error patterns:

Pattern	Meaning	Quick Fix
Blacklist / Banned	Sender address is on maker's deny list	Use a different sender address
Insufficient Liquidity	Maker doesn't have enough balance	Retry or exclude the source
Amount Too Small/Large	Trade size outside maker's range	Adjust amountIn
Market Moved	Price changed between route and build	Fetch fresh route and retry

For any error not listed here, refer to ${CLAUDE_PLUGIN_ROOT}/skills/error-handling/SKILL.md.

Step 6: Format the Output

Present the results:

## KyberSwap Swap Transaction

**{amount} {tokenIn} → {amountOut} {tokenOut}** on {Chain}

| Detail | Value |
|---|---|
| Input | {amount} {tokenIn} (~${amountInUsd}) |
| Expected output | {amountOut} {tokenOut} (~${amountOutUsd}) |
| Minimum output (after slippage) | {minAmountOut} {tokenOut} |
| Slippage tolerance | {slippageTolerance/100}% |
| Gas estimate | {gas} units (~${gasUsd}) |
| L1 fee (L2 only) | ~${additionalCostUsd} — {additionalCostMessage} *(omit on L1 chains or if absent)* |

### Transaction Details

| Field | Value |
|---|---|
| To (Router) | `{routerAddress}` |
| Value | `{value}` (in wei — non-zero only for native token input) |
| Data | `{encodedCalldata}` |
| Sender | `{sender}` |
| Recipient | `{recipient}` |

> **WARNING:** Review the transaction details carefully before submitting on-chain. This plugin does NOT submit transactions — it only builds the calldata. You are responsible for verifying the router address, amounts, and calldata before signing and broadcasting.

Structured JSON Output

After the markdown table, always include a JSON code block so other plugins or agents can consume the result programmatically:

```json
{
  "type": "kyberswap-swap",
  "chain": "{chain}",
  "tokenIn": {
    "symbol": "{tokenIn}",
    "address": "{tokenInAddress}",
    "decimals": {tokenInDecimals},
    "amount": "{amount}",
    "amountWei": "{amountInWei}",
    "amountUsd": "{amountInUsd}"
  },
  "tokenOut": {
    "symbol": "{tokenOut}",
    "address": "{tokenOutAddress}",
    "decimals": {tokenOutDecimals},
    "amount": "{amountOut}",
    "amountWei": "{amountOutWei}",
    "amountUsd": "{amountOutUsd}"
  },
  "tx": {
    "to": "{routerAddress}",
    "data": "{encodedCalldata}",
    "value": "{transactionValue}",
    "gas": "{gas}",
    "gasUsd": "{gasUsd}"
  },
  "sender": "{sender}",
  "recipient": "{recipient}",
  "slippageBps": {slippageTolerance}
}
```

This JSON block enables downstream agents or plugins to parse the swap result without scraping the markdown table.

Calculating minimum output: If outputChange is provided in the build response, use:

minAmountOut = amountOut from build response / 10^(tokenOut decimals)

Value field: Use the transactionValue field from the build response directly. This is the value for the on-chain transaction (in wei). It will be non-zero only for native token input. Do not compute this manually.

Step 7: ERC-20 Approval Reminder

If tokenIn is not the native token, add this note after the transaction details:

### Token Approval Required

Before submitting this swap, you must approve the KyberSwap router to spend your {tokenIn}:

- **Token contract:** `{tokenIn address}`
- **Spender (router):** `{routerAddress}`
- **Amount:** `{amountInWei}` (exact amount, recommended) or `type(uint256).max` (unlimited — see warning below)

> **Security warning:** Unlimited approvals (`type(uint256).max`) are convenient but risky. If the router contract is ever compromised, an attacker could drain all approved tokens from your wallet. For large holdings, prefer **exact-amount approvals** matching `amountInWei`. Only use unlimited approvals with wallets holding limited funds.

Use your wallet or a tool like `cast` to send the approval transaction first.

Important Notes

• Always read both ${CLAUDE_PLUGIN_ROOT}/references/token-registry.md and ${CLAUDE_PLUGIN_ROOT}/references/api-reference.md before making API calls.
• Never guess token addresses or sender addresses.
• If the user doesn't specify a chain, default to ethereum.
• If the user specifies a chain not listed in references/api-reference.md, query https://common-service.kyberswap.com/api/v1/aggregator/supported-chains via WebFetch to check if the chain is supported. Look for a matching chainName with state: "active" or state: "new". Use the chainName value as the path slug.
• If the user doesn't specify slippage, use the smart defaults from the Slippage Defaults table.
• Routes should not be cached for more than 5-10 seconds. If the build step fails, re-fetch the route from the GET endpoint and retry.
• This skill does NOT submit transactions on-chain. It only builds the calldata.

Additional Resources

Reference Files

• ${CLAUDE_PLUGIN_ROOT}/references/api-reference.md — Full API specification, error codes, rate limiting
• ${CLAUDE_PLUGIN_ROOT}/references/token-registry.md — Token addresses and decimals by chain

Example Files

Working examples in ${CLAUDE_PLUGIN_ROOT}/skills/swap-build/references/:

• basic-swap.md — Simple ETH to USDC swap with native token input
• erc20-swap.md — ERC-20 swap requiring token approval

Troubleshooting

For error codes not covered in Steps 4/5b, or for advanced debugging (full PMM/RFQ error catalog, on-chain revert analysis), refer to ${CLAUDE_PLUGIN_ROOT}/skills/error-handling/SKILL.md.