V4 Hook Generator

v4 Hook Generator

Generate Uniswap v4 hook contracts via the OpenZeppelin Contracts Wizard MCP tool. This skill guides you through selecting the right hook type, configuring permissions and utilities, assembling the canonical MCP JSON, and invoking the MCP tool to produce ready-to-compile Solidity code.

> Security companion: Generated hook code touches fund-handling contracts. Always apply the > v4-security-foundations skill immediately after generation to audit permissions, delta > accounting, and access control before deploying to any network.

When to Use This Skill

Use this skill when you need to:

• Scaffold a new Uniswap v4 hook contract from scratch
• Select the right base hook type for a specific use case (fees, MEV protection, oracles, etc.)
• Configure hook permissions, utility libraries, shares, and access control
• Produce the canonical MCP tool call JSON to invoke the OpenZeppelin Contracts Wizard
• Understand trade-offs between hook configuration options before committing to an implementation

Prerequisite / companion skill: v4-security-foundations — run it before writing custom logic and again before deployment. Hook misconfiguration can drain user funds.

Hook Type Decision Table

Choose the base hook type that matches your primary goal. If your hook has multiple goals, choose the type that covers the most critical concern and layer additional logic on top.

| Goal | Use Hook | | -------------------- | -------------------------- | | Custom swap logic | BaseHook | | Async/delayed swaps | BaseAsyncSwap | | Hook-owned liquidity | BaseCustomAccounting | | Custom curve | BaseCustomCurve | | Dynamic LP fees | BaseDynamicFee | | Dynamic swap fees | BaseOverrideFee | | Post-swap fees | BaseDynamicAfterFee | | Fixed hook fees | BaseHookFee | | MEV protection | AntiSandwichHook | | JIT protection | LiquidityPenaltyHook | | Limit orders | LimitOrderHook | | Yield on idle | ReHypothecationHook | | Oracle | BaseOracleHook | | V3-compatible oracle | OracleHookWithV3Adapters |

Selection tips:

• BaseHook is the general-purpose starting point — choose a specialized type only when the

built-in logic provides concrete value.

• BaseCustomCurve replaces the entire AMM math; only use it if you are implementing a novel

pricing algorithm.

• AntiSandwichHook and LiquidityPenaltyHook both address MEV but target different actors

(traders vs. JIT LPs). Clarify which attack vector you are mitigating.

• OracleHookWithV3Adapters is appropriate when downstream integrations expect a Uniswap v3

IUniswapV3Pool-compatible oracle interface.

Minimal Decision Checklist

Before calling the MCP tool, confirm all six decisions:

1. Hook type — chosen from the decision table above
2. Permissions to enable — only the callbacks your logic actually uses (beforeSwap, afterSwap, etc.)
3. Utility libraries — currencySettler, safeCast, transientStorage as needed
4. Shares — false, ERC20, ERC6909, or ERC1155
5. Access control — ownable, roles, or managed
6. Hook inputs — blockNumberOffset, maxAbsTickDelta (only for hook types that use them)

Permission Configuration

All 14 permission flags with guidance on when to enable each. Start with all flags false and enable only what your hook logic requires. Every enabled permission increases the hook's attack surface and requires a specific bit to be set in the hook's deployed address (see address encoding note below).

| Permission Flag | Enable When | Risk | | --------------------------------- | --------------------------------------------------------------------------------------------------------------- | -------- | | beforeInitialize | You need to validate or restrict pool creation params | LOW | | afterInitialize | You need to set up state after a pool is created | LOW | | beforeAddLiquidity | You need to gate or transform LP deposits | MEDIUM | | afterAddLiquidity | You track LP positions or distribute rewards | LOW | | beforeRemoveLiquidity | You need lock-up periods or fee-on-exit logic | HIGH | | afterRemoveLiquidity | You track position removals for accounting | LOW | | beforeSwap | You modify swap behavior, apply dynamic fees, or block | HIGH | | afterSwap | You observe final swap state for oracles or accounting | MEDIUM | | beforeDonate | You restrict who may donate to the pool | LOW | | afterDonate | You track donation events | LOW | | beforeSwapReturnDelta | You implement custom AMM curves or JIT liquidity (CRITICAL: NoOp attack vector — see v4-security-foundations) | CRITICAL | | afterSwapReturnDelta | You extract a hook fee from swap output | HIGH | | afterAddLiquidityReturnDelta | You adjust LP token amounts on deposit | HIGH | | afterRemoveLiquidityReturnDelta | You adjust withdrawal amounts | HIGH |

Address encoding note: Permissions are encoded as bits in the hook contract's deployed address. The address must have the correct bits set at deployment time or the PoolManager will revert. Use HookMiner (from v4-periphery) to mine a salt that produces an address with the correct bit pattern. Never change permissions after deployment — the address is immutable.

Utility Library Selection

Three optional utility libraries can be included in the generated hook. Include only what your hook logic uses.

| Library | Include When | | ------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | | currencySettler | Your hook moves tokens between itself and the PoolManager (e.g., custom accounting, fee collection) | | safeCast | Your hook performs arithmetic that could overflow when casting between integer types | | transientStorage | Your hook needs to pass data between callbacks within a single transaction without persisting to storage (requires EVM Cancun or later, Solidity >= 0.8.24) |

Guidance:

• currencySettler is almost always needed when beforeSwapReturnDelta,

afterSwapReturnDelta, afterAddLiquidityReturnDelta, or afterRemoveLiquidityReturnDelta are enabled — it provides settle and take helpers that implement the correct sync → transfer → settle sequence.

• transientStorage is a gas-efficient alternative to storage slots for intra-transaction state.

Use it to pass a flag or value from beforeSwap to afterSwap without paying 20k gas for a cold SSTORE.

• safeCast is advisable whenever you compute amounts derived from int256/uint256 conversions,

especially for fee calculations.

Shares Configuration

The shares option controls whether the generated hook issues a token representing user shares (e.g., LP positions in hook-owned liquidity pools).

| Option | Description | Use When | | --------- | -------------------------------------------------------------------------------------------- | -------------------------------------------------------- | | false | No share token — hook does not track ownership of deposited assets | Simple hooks that do not hold user funds | | ERC20 | Fungible share token — one token represents proportional ownership of all hook-held assets | Hook-managed liquidity pools with interchangeable shares | | ERC6909 | Multi-token (minimal) — one contract manages many token IDs with lower overhead than ERC1155 | Hook manages multiple distinct asset classes efficiently | | ERC1155 | Multi-token (standard) — full ERC1155 with metadata URI support | Hook needs broad wallet and marketplace compatibility |

Trade-offs:

• false: smallest bytecode, no share accounting overhead; appropriate for fee hooks and oracles.
• ERC20: simplest fungible share; good DeFi composability (e.g., used as collateral).
• ERC6909: gas-efficient multi-token with a minimal interface; preferred for new protocol designs.
• ERC1155: widest ecosystem support (wallets, explorers, NFT marketplaces); higher gas cost per

transfer than ERC6909.

Access Control Options

The access option shapes the constructor and administrative interface of the generated hook.

| Option | Constructor Shape | Use When | | --------- | ------------------------------------------------- | ---------------------------------------------------------------------------- | | ownable | constructor(IPoolManager, address initialOwner) | Single owner controls all admin functions | | roles | constructor(IPoolManager, address admin) | Multiple roles with granular permissions (OpenZeppelin AccessControl) | | managed | constructor(IPoolManager, address authority) | External authority contract governs permissions (OpenZeppelin AccessManaged) |

Guidance:

• ownable is the simplest — one address can perform all privileged operations. Suitable for

early-stage hooks and personal tools.

• roles adds ADMIN_ROLE, PAUSER_ROLE, etc. via OpenZeppelin AccessControl. Use when

different team members need different privileges (e.g., a keeper bot that can update fees but cannot upgrade the contract).

• managed delegates all permission checks to a separate AccessManager contract. Use when

you need a unified governance layer across multiple contracts or want timelocked admin actions.

> Note: Changing the access option changes the constructor signature. Update deployment > scripts and initialization logic accordingly. When using ownable, ensure the initialOwner > is not the zero address — OpenZeppelin's Ownable reverts on zero address since v5.

Hook Inputs Reference

Some hook types accept numeric configuration inputs that tune behavior. These are passed as the inputs object in the MCP tool call.

| Input | Type | Used By | Description | | ------------------- | --------- | ------------------------------------------ | ---------------------------------------------------------------------- | | blockNumberOffset | uint256 | AntiSandwichHook, LiquidityPenaltyHook | Number of blocks before sandwich/JIT detection window opens | | maxAbsTickDelta | int24 | AntiSandwichHook | Maximum tick movement allowed per block before MEV protection triggers |

For hook types that do not use these inputs, omit the inputs field or pass an empty object {}. Passing unsupported inputs to the MCP tool will not cause an error but the values will be ignored.

MCP Tool Call (Canonical)

The OpenZeppelin Contracts Wizard exposes a generate_hook MCP tool. The following is the canonical JSON schema — populate each field according to your decisions from the sections above, then pass this object as the tool's argument.

{
  "hook": "BaseHook",
  "name": "MyHook",
  "pausable": false,
  "currencySettler": true,
  "safeCast": true,
  "transientStorage": false,
  "shares": { "options": false },
  "permissions": {
    "beforeInitialize": false,
    "afterInitialize": false,
    "beforeAddLiquidity": false,
    "beforeRemoveLiquidity": false,
    "afterAddLiquidity": false,
    "afterRemoveLiquidity": false,
    "beforeSwap": true,
    "afterSwap": false,
    "beforeDonate": false,
    "afterDonate": false,
    "beforeSwapReturnDelta": false,
    "afterSwapReturnDelta": false,
    "afterAddLiquidityReturnDelta": false,
    "afterRemoveLiquidityReturnDelta": false
  },
  "inputs": {
    "blockNumberOffset": 1,
    "maxAbsTickDelta": 100
  },
  "access": "ownable",
  "info": { "license": "MIT" }
}

Field notes:

• hook: string — one of the 14 hook types from the decision table
• name: string — the Solidity contract name (PascalCase, no spaces)
• pausable: boolean — wraps the hook in OpenZeppelin Pausable; adds pause()/unpause() admin functions
• shares.options: false | "ERC20" | "ERC6909" | "ERC1155"
• access: "ownable" | "roles" | "managed"
• info.license: SPDX license identifier — use "MIT" for open-source hooks
• inputs: omit or pass {} for hook types that do not use blockNumberOffset/maxAbsTickDelta

Workflow: Gather → Configure → Generate → Secure

Follow these steps in order every time you use this skill.

Step 1: Gather Requirements

Ask the user (or infer from context):

1. What is the hook's primary goal? (Map to the decision table.)
2. Which lifecycle events does the hook need to intercept? (Map to permissions.)
3. Does the hook hold or move user funds? (Determines currencySettler and shares.)
4. Who administers the hook? (Single owner, role-based team, or external governance?)
5. Does the hook need to pass state between callbacks within a single transaction?
6. Is this for a chain with EVM Cancun support? (Required for transientStorage.)

Step 2: Select Hook Type

Using the decision table, identify the single best hook type. If the user's goal maps to multiple types, explain the trade-offs and ask them to confirm. Document the chosen type and the reasoning.

Step 3: Configure All Six Decisions

Work through the minimal decision checklist:

1. Set hook to the chosen type.
2. Set each permission flag — default false, enable only what the logic requires.
3. Set currencySettler, safeCast, transientStorage based on utility library guidance.
4. Set shares.options based on shares guidance.
5. Set access based on access control guidance.
6. Set inputs only if the hook type uses blockNumberOffset or maxAbsTickDelta.

Step 4: Assemble and Call the MCP Tool

Construct the JSON object from Step 3 and call the OpenZeppelin Contracts Wizard MCP tool with it. The tool returns Solidity source code — it does not write files automatically.

After receiving the generated code:

1. Display the code t

…

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Uniswap
• Source: Uniswap/uniswap-ai
• License: MIT
• Homepage: https://developers.uniswap.org

Install and usage instructions live in the source repository linked above.