prepare_curve_swap

SERVERVaultPilot MCP SOURCEvaultpilot-mcp

High RISK CLASS

Category Execute

Parameters 105 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-szhygulin-vaultpilot-mcp/prepare-curve-swap.md

WHAT IT DOES

What prepare_curve_swap does on VaultPilot MCP

AI agents invoke prepare_curve_swap to trigger actions in VaultPilot MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

Parameter	Type	Required	Description
`pool`	string	Yes	Curve pool address. Must be the canonical legacy stETH/ETH pool (0xDC24316b9AE028F1497c275EB9192a3Ea0f67022) or a stable_ng factory plain pool. Meta pools, cryp
`amount`	string	Yes	Human-readable decimal input amount in the from-token (e.g. "1.5"). Decimals are read from the from-token contract; native = 18.
`minOut`	string	—	Explicit minimum output in the to-token's wei (decimal-string uint256). Takes precedence over `slippageBps` when both are provided.
`wallet`	string	Yes	0x EVM wallet address that will sign the tx.
`toToken`	object	Yes	Token to receive. Same rules as `fromToken`. Must differ from `fromToken` and both must appear in the pool's `coins` array.
`fromToken`	object	Yes	Token to spend. Pass `"native"` only for pools whose `coins(i)` returns the ETH sentinel (0xeeee...eeee) at some index — currently the legacy stETH/ETH pool. Fo
`approvalCap`	string	—	Cap on the ERC-20 approval preceding this action. Omit for "unlimited" (standard DeFi UX — fewer follow-up approvals). Pass "exact" to approve only what this ac
`slippageBps`	integer	—	Slippage tolerance in basis points (50 = 0.5%). When set, `min_dy = get_dy(i,j,dx) * (1 - slippageBps/10000)`. Either `slippageBps` or `minOut` is required — th
`acknowledgeHighSlippage`	boolean	—	Required when `slippageBps > 100` (1%). Same gate as `prepare_swap` — sandwich-MEV bots target wide-slippage txs.
`acknowledgeNonAllowlistedSpender`	boolean	—	AFFIRMATIVE GATE — required whenever `fromToken` is an ERC-20 (the approve leg targets the Curve pool, which is NOT in the global protocol approve-allowlist: Aa

Parameters from the server's own tool schema.

RISK

Why prepare_curve_swap is rated High

This tool builds and prepares a swap transaction on the Ethereum blockchain via the Curve protocol. While it produces an 'unsigned' transaction (suggesting it doesn't directly submit), it constructs executable financial operations (token swaps) that, once signed and submitted, move crypto assets. The tool itself is the Execute step in a sign-then-broadcast workflow common in self-custodial crypto systems.

From the tool's definition 'Build an unsigned Curve swap on Ethereum' — constructs a DeFi swap transaction involving token exchange on Curve protocol, triggering external on-chain operations with slippage controls and pool interactions

Risk signalsHigh parameter count (10 properties) · Bulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs prepare_curve_swap safely

PolicyLayer is an MCP gateway: it sits between your AI agents and VaultPilot MCP, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For prepare_curve_swap, this is the rule to start with:

prepare_curve_swap Rate-limited

prepare_curve_swap stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "prepare_curve_swap": {
      "limits": [
        {
          "counter": "prepare_curve_swap_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect VaultPilot MCP, apply this rule, and every prepare_curve_swap call is checked against it from then on.

FAQ

Questions about prepare_curve_swap

What does the prepare_curve_swap tool do? +

Build an unsigned Curve swap on Ethereum. Issue #615. Supports the canonical legacy stETH/ETH pool (0xDC24316b9AE028F1497c275EB9192a3Ea0f67022 — historically the tightest-spread venue for stETH↔ETH) and any plain pool registered with the stable_ng factory (covers crvUSD/USDC, USDe/USDC, etc.). Pass pool + fromToken + toToken; the tool resolves coin indices from the pool's coins array. Use fromToken: "native" for the ETH leg of the stETH/ETH pool (the only currently-supported pool whose coins(i) returns the ETH sentinel). Slippage gate REQUIRED: slippageBps (server reads get_dy and applies the cap) or minOut (explicit decimal-string uint256). The pool's exchange() accepts min_dy=0 silently — defaulting to that would let MEV extract the entire output. ERC-20 inputs chain an approval to the pool automatically. Rejected: meta pools (use exchange_underlying — different ABI), cryptoswap / tricrypto / older legacy stable pools (uint256 indices, use_eth flag — different selectors). For unsupported Curve pairs, fall back to prepare_swap (LiFi). It is categorised as a Execute tool in the VaultPilot MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

What parameters does prepare_curve_swap accept? +

prepare_curve_swap accepts 10 parameters: pool, amount, minOut, wallet, toToken, fromToken, approvalCap, slippageBps, acknowledgeHighSlippage, acknowledgeNonAllowlistedSpender. Required: pool, amount, wallet, toToken, fromToken. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on prepare_curve_swap? +

Register the VaultPilot MCP server in PolicyLayer and add a rule for prepare_curve_swap: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches VaultPilot MCP. Nothing to install.

What risk level is prepare_curve_swap? +

prepare_curve_swap is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit prepare_curve_swap? +

Yes. Add a rate_limit block to the prepare_curve_swap rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block prepare_curve_swap completely? +

Set action: deny in the PolicyLayer policy for prepare_curve_swap. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides prepare_curve_swap? +

prepare_curve_swap is provided by the VaultPilot MCP server (vaultpilot-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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