Setup Local Testnet

Overview

Spins up a local Anvil testnet forking a live chain with all Uniswap contracts available, pre-funded test accounts, and real pool state. This is the foundation for all local testing -- every other testnet skill depends on it.

Why this is 10x better than doing it manually:

1. One command: Instead of writing 30+ lines of shell script to start Anvil, impersonate whales, fund accounts, and verify contracts, you say "set up a local testnet" and it's done.
2. Pre-funded accounts: Each test account gets 10,000 ETH plus 1M USDC, 1M USDT, 10K DAI, 100 WETH, and 10K UNI -- ready for any testing scenario.
3. Real pool state: Fork mode gives you every Uniswap pool with real liquidity, real prices, and real tick state. No mocking required.
4. Contract discovery: Returns all relevant Uniswap contract addresses (V3Factory, NonfungiblePositionManager, UniversalRouter, Permit2, QuoterV2) so you can immediately interact with them.
5. Port management: Automatically finds an available port, handles conflicts, and cleans up previous testnets.
6. Follow-up integration: Output is designed to feed directly into create-test-pool and time-travel skills.

When to Use

Activate when the user says anything like:

• "Set up a local testnet"
• "Start a local Anvil fork"
• "I need a test environment for Uniswap"
• "Fork Ethereum locally"
• "Set up a dev environment"
• "I want to test without spending real gas"
• "Spin up Anvil with Uniswap"
• "Create a test environment for my agent"

Do NOT use when the user already has a testnet running and just wants to add pools (use create-test-pool) or advance time (use time-travel).

Parameters

Workflow

Step 1: Check Prerequisites

Before calling the MCP tool, verify the environment:

1. Anvil availability: The tool will return a clear error if Anvil is not installed. If you see TESTNET_ANVIL_NOT_FOUND, tell the user:

   Anvil (Foundry) is required but not installed.
   Install: curl -L https://foundry.paradigm.xyz | bash && foundryup
   

2. Network access: Fork mode requires network access to the chain's RPC. If you see TESTNET_STARTUP_TIMEOUT, suggest checking network connectivity or trying a different chain.

Step 2: Extract Parameters

Parse the user's request for any specific requirements:

• Chain preference: "fork Base" → forkFrom: "base"
• Block number: "at block 19000000" → blockNumber: 19000000
• Account count: "5 test accounts" → fundedAccounts: 5
• No funding: "empty testnet" → seedLiquidity: false

If the user doesn't specify, use all defaults (fork Ethereum, 3 funded accounts, seed liquidity).

Step 3: Call setup_local_testnet

Call mcp__uniswap__setup_local_testnet with the extracted parameters.

Step 4: Present Results

Format the response as a rich summary:

Local Testnet Ready

  RPC URL:    http://127.0.0.1:8545
  Chain ID:   31337
  Mode:       Fork of Ethereum at block 19,234,567

  Funded Accounts:
  ┌──────────────────────────────────────────────────────────────────────┐
  │ #  Address                                    ETH       USDC        │
  │ 1  0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266 10,000    1,000,000  │
  │ 2  0x70997970C51812dc3A010C7d01b50e0d17dc79C8 10,000    1,000,000  │
  │ 3  0x3C44CdDdB6a900fa2b585dd299e03d12FA4293BC 10,000    1,000,000  │
  └──────────────────────────────────────────────────────────────────────┘

  Key Contracts:
    V3Factory:                      0x1F98431c8aD98523631AE4a59f267346ea31F984
    NonfungiblePositionManager:     0xC36442b4a4522E871399CD717aBDD847Ab11FE88
    UniversalRouter:                0x3fC91A3afd70395Cd496C647d5a6CC9D4B2b7FAD
    Permit2:                        0x000000000022D473030F116dDEE9F6B43aC78BA3
    QuoterV2:                       0x61fFE014bA17989E743c5F6cB21bF9697530B21e

  Available Pools (from fork):
    USDC/WETH 0.05% (V3)  — 0x88e6A0c2dDD26FEEb64F039a2c41296FcB3f5640
    USDC/WETH 0.30% (V3)  — 0x8ad599c3A0ff1De082011EFDDc58f1908eb6e6D8
    USDT/WETH 0.30% (V3)  — 0x4e68Ccd3E89f51C3074ca5072bbAC773960dFa36
    WBTC/WETH 0.30% (V3)  — 0xCBCdF9626bC03E24f779434178A73a0B4bad62eD

  Private Keys (for wallet config):
    Account #1: 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80
    Account #2: 0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d
    Account #3: 0x5de4111afa1a4b94908f83103eb1f1706367c2e68ca870fc3fb9a804cdab365a

Step 5: Suggest Next Steps

Always end with actionable follow-ups:

  Next Steps:
  - Create a custom pool: "Create a WETH/DAI pool with thin liquidity"
  - Test time-dependent logic: "Advance time by 7 days"
  - Test a swap: "Get a quote for 1 WETH → USDC on the local testnet"
  - Fund more tokens: "Fund account #1 with 10,000 WBTC"
  - Configure your MCP server: Set RPC_URL_1=http://127.0.0.1:8545 in .env

Important Notes

• Anvil must be installed. This skill requires Foundry's Anvil. If not installed, provide the installation command.
• Fork mode requires network access. The initial fork downloads state from the live chain's RPC. Subsequent operations are local.
• Port conflicts are handled automatically. If port 8545 is in use, the tool finds the next available port.
• Previous testnets are cleaned up. Starting a new testnet kills any existing one.
• Private keys are Anvil defaults. These are well-known test keys -- never use them on mainnet.
• The testnet persists until the MCP server process exits or a new testnet is started.

Error Handling