# Setup Local Testnet > Spin up a local Anvil testnet with Uniswap deployed and pre-seeded liquidity. One command gives you a full development environment with funded accounts, real Uniswap pools, and zero gas costs. Use when developing, testing, or demoing Uniswap agent workflows. - Skill: `johnalbertini14-glitch/setup-local-testnet` (Agent Skill, multi-file: 3 files) - Install (CLI): `npx skillmds@latest add johnalbertini14-glitch/setup-local-testnet` - Raw SKILL.md: https://api.skillmd.com/api/skills/johnalbertini14-glitch/setup-local-testnet/raw - Safety review: pending (external: skill-scanner PASS, skillspector CAUTION) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: johnalbertini14-glitch (https://skillmd.com/u/johnalbertini14-glitch) - Updated: 2026-09-09 - Page: https://skillmd.com/skills/johnalbertini14-glitch/setup-local-testnet --- # 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 | Parameter | Required | Default | How to Extract | | -------------- | -------- | ---------- | --------------------------------------------------------------------- | | mode | No | fork | "fork" or "mock" -- fork is the default and recommended | | forkFrom | No | ethereum | "ethereum", "base", "arbitrum", "optimism", "polygon" | | blockNumber | No | latest | Specific block number if the user mentions one | | seedLiquidity | No | true | Set to false only if user says "empty testnet" or "no tokens" | | fundedAccounts | No | 3 | Number of accounts (1-5) if user specifies | | port | No | auto | Specific port if user mentions one | ## 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: ```text 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: ```text 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 | Error | User-Facing Message | Suggested Action | | ------------------------------ | ------------------------------------------------------------------------ | --------------------------------------------------------------- | | `TESTNET_ANVIL_NOT_FOUND` | "Anvil (Foundry) is not installed." | Install: `curl -L https://foundry.paradigm.xyz \| bash && foundryup` | | `TESTNET_STARTUP_TIMEOUT` | "Anvil did not start within 30s. Fork RPC may be unreachable." | Check network, try a different chain, or retry | | `TESTNET_INVALID_FORK_CHAIN` | "Chain X is not supported for forking." | Use ethereum, base, arbitrum, optimism, or polygon | | `TESTNET_MOCK_NOT_IMPLEMENTED` | "Mock mode is not yet implemented." | Use fork mode instead | | `TESTNET_SETUP_FAILED` | "Failed to set up testnet: {reason}" | Check Anvil installation and network access |