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:

Hook type — chosen from the decision table above
Permissions to enable — only the callbacks your logic actually uses (
```
beforeSwap
```
,
```
afterSwap
```
, etc.)
Utility libraries —
```
currencySettler
```
,
```
safeCast
```
,
```
transientStorage
```
as needed
Shares —
```
false
```
,
```
ERC20
```
,
```
ERC6909
```
, or
```
ERC1155
```
Access control —
```
ownable
```
,
```
roles
```
, or
```
managed
```
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.

json

{
  "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):

What is the hook's primary goal? (Map to the decision table.)
Which lifecycle events does the hook need to intercept? (Map to permissions.)
Does the hook hold or move user funds? (Determines
```
currencySettler
```
and
```
shares
```
.)
Who administers the hook? (Single owner, role-based team, or external governance?)
Does the hook need to pass state between callbacks within a single transaction?
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:

Set
```
hook
```
to the chosen type.
Set each permission flag — default
```
false
```
, enable only what the logic requires.
Set
```
currencySettler
```
,
```
safeCast
```
,
```
transientStorage
```
based on utility library guidance.
Set
```
shares.options
```
based on shares guidance.
Set
```
access
```
based on access control guidance.
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:

Display the code to the user.
Explain the key generated sections (constructor,
```
getHookPermissions
```
, enabled callbacks).
Note any manual steps required (HookMiner for address mining, deployment script updates for constructor args if
```
access
```
is
```
roles
```
or
```
managed
```
).

Step 5: Apply Security Foundations

Always remind the user — and invoke

v4-security-foundations

— before the code is deployed:

Verify all enabled callbacks check
```
msg.sender == address(poolManager)
```
.
Review any enabled
```
*ReturnDelta
```
permissions for NoOp attack exposure.
Confirm delta accounting sums to zero for every execution path.
Run the full pre-deployment audit checklist from
```
v4-security-foundations
```
.

Important Notes

Access control changes constructor shape: Choosing
```
ownable
```
adds an
```
initialOwner
```
parameter;
```
roles
```
adds an
```
admin
```
parameter;
```
managed
```
adds an
```
authority
```
parameter. Update deployment scripts and factory contracts accordingly.
Permissions encode in the hook address: Each enabled permission flag corresponds to a specific bit in the lower bytes of the hook's deployed address. The PoolManager validates these bits on every callback. Use
```
HookMiner
```
from
```
v4-periphery
```
to mine a deployment salt that produces a matching address.
MCP returns code only — it does not write files: The generated Solidity is returned as a string. You must write it to disk yourself (e.g.,
```
packages/contracts/src/hooks/MyHook.sol
```
).

Related Skills

```
v4-security-foundations
```
— Run this after generation. Security audit for Uniswap v4 hooks: permission risk matrix, NoOp attack patterns, delta accounting, access control verification, and the full pre-deployment audit checklist. Generated hook code should never be deployed without completing this review.
```
viem-integration
```
— Deploy generated hook contracts and interact with them using viem/wagmi
```
v4-sdk-integration
```
— Interact with deployed hooks via the Uniswap v4 SDK

v4-hook-generator

NPX Install

Tags

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