---
title: Configuration Reference
category: reference
date: 2025-11-28
status: active
---
# Configuration Reference
Complete reference for all configuration options in MCP Anvil Tools.
## Environment Variables
### Server Configuration
| Variable | Required | Default | Description |
|----------|----------|---------|-------------|
| `AUDIT_MCP_PORT` | No | `3000` | HTTP server port |
| `NODE_ENV` | No | `development` | Environment mode |
### RPC Endpoints
| Variable | Required | Default | Description |
|----------|----------|---------|-------------|
| `MAINNET_RPC_URL` | No | - | Ethereum mainnet RPC |
| `SEPOLIA_RPC_URL` | No | - | Sepolia testnet RPC |
| `ARBITRUM_RPC_URL` | No | - | Arbitrum mainnet RPC |
| `OPTIMISM_RPC_URL` | No | - | Optimism mainnet RPC |
| `BASE_RPC_URL` | No | - | Base mainnet RPC |
### API Keys
| Variable | Required | Default | Description |
|----------|----------|---------|-------------|
| `ETHERSCAN_API_KEY` | No | - | For source code verification |
| `ALCHEMY_API_KEY` | No | - | Alchemy RPC authentication |
| `INFURA_API_KEY` | No | - | Infura RPC authentication |
### Anvil Configuration
| Variable | Required | Default | Description |
|----------|----------|---------|-------------|
| `ANVIL_PORT_START` | No | `8545` | Starting port for Anvil instances |
| `ANVIL_PORT_END` | No | `8555` | Ending port for Anvil instances |
| `ANVIL_FORK_URL` | No | - | Default fork URL for new instances |
| `ANVIL_BLOCK_TIME` | No | - | Block time in seconds (auto-mine if omitted) |
### Database
| Variable | Required | Default | Description |
|----------|----------|---------|-------------|
| `DATABASE_PATH` | No | `./data/audit.db` | SQLite database location |
## Example .env File
```bash
# Server
AUDIT_MCP_PORT=3000
NODE_ENV=production
# RPC Endpoints (add your keys)
MAINNET_RPC_URL=https://eth-mainnet.g.alchemy.com/v2/YOUR_KEY
SEPOLIA_RPC_URL=https://eth-sepolia.g.alchemy.com/v2/YOUR_KEY
# API Keys
ETHERSCAN_API_KEY=your_etherscan_api_key
ALCHEMY_API_KEY=your_alchemy_api_key
# Anvil
ANVIL_PORT_START=8545
ANVIL_PORT_END=8555
# Database
DATABASE_PATH=./data/audit.db
```
## Claude Desktop Configuration
### macOS
Config location: `~/Library/Application Support/Claude/claude_desktop_config.json`
### Windows
Config location: `%APPDATA%\Claude\claude_desktop_config.json`
### Linux
Config location: `~/.config/Claude/claude_desktop_config.json`
### Configuration Structure
```json
{
"mcpServers": {
"anvil-tools": {
"command": "node",
"args": [
"/absolute/path/to/mcp-anvil-tools/dist/index.js",
"--stdio"
],
"env": {
"AUDIT_MCP_PORT": "3000",
"MAINNET_RPC_URL": "https://eth-mainnet.g.alchemy.com/v2/YOUR_KEY",
"ETHERSCAN_API_KEY": "your_etherscan_api_key"
}
}
}
}
```
**Important Notes:**
- Use **absolute paths** only (no `~` or relative paths)
- Include the `--stdio` flag in args
- All env vars are optional but recommended
## Transport Modes
### HTTP/SSE Mode
```bash
npm start
# or
node dist/index.js
```
**Endpoints:**
| Endpoint | Method | Description |
|----------|--------|-------------|
| `/health` | GET | Health check |
| `/metrics` | GET | Server metrics |
| `/sse` | GET | SSE connection for MCP |
| `/messages` | POST | MCP message endpoint |
### stdio Mode
```bash
npm run start:stdio
# or
node dist/index.js --stdio
```
- JSON-RPC over stdin/stdout
- Logs output to stderr
- Required for Claude Desktop integration
## Zod Validation
All configuration is validated with Zod schemas at startup:
```typescript
const ConfigSchema = z.object({
port: z.coerce.number().default(3000),
nodeEnv: z.enum(['development', 'production', 'test']).default('development'),
mainnetRpcUrl: z.string().url().optional(),
etherscanApiKey: z.string().optional(),
anvilPortStart: z.coerce.number().default(8545),
anvilPortEnd: z.coerce.number().default(8555),
databasePath: z.string().default('./data/audit.db'),
});
```
Invalid configuration causes the server to fail at startup with descriptive error messages.
## Network Defaults
When `rpc` parameter is omitted from tool calls:
| Context | Default RPC |
|---------|-------------|
| Local development | `http://localhost:8545` |
| Configured mainnet | Value of `MAINNET_RPC_URL` |
## Security Considerations
1. **Never commit `.env` files** - Contains API keys
2. **Use environment variables** - Not hardcoded values
3. **Restrict Anvil ports** - Limit port range in production
4. **Impersonation blocked** - Only works on Anvil nodes
## Related Documents
- [Getting Started Guide](../guides/guide-getting-started-2025-11-28.md)
- [Claude Desktop Integration](../guides/guide-claude-desktop-2025-11-28.md)
- [API Tools Reference](../api/api-tools-reference-2025-11-28.md)
