/**
* MCP Tool: getGasPrices
*
* Get current gas prices for EVM-compatible blockchains.
* Supports Ethereum, Arbitrum, Base, Polygon, Optimism, and Avalanche.
*/
import { gasFetcher, type GasPrice } from '../apis/gas.js';
import { ValidationError } from '@boosty/mcp-shared';
// ============================================================================
// Input/Output Types
// ============================================================================
export interface GetGasPricesInput {
/** Chain name (optional - returns all chains if not specified) */
chain?: string;
}
export interface GetGasPricesOutput {
gasPrices: GasPrice[];
supportedChains: string[];
timestamp: string;
}
// ============================================================================
// Tool Definition (MCP Schema)
// ============================================================================
export const getGasPricesDefinition = {
name: 'getGasPrices',
description:
'Get current gas prices for EVM blockchains. Returns low, medium, and high gas estimates in gwei. Supports Ethereum, Arbitrum, Base, Polygon, Optimism, and Avalanche.',
inputSchema: {
type: 'object' as const,
properties: {
chain: {
type: 'string',
description:
'Chain name (ethereum, arbitrum, base, polygon, optimism, avalanche). If not specified, returns gas prices for all supported chains.',
enum: ['ethereum', 'arbitrum', 'base', 'polygon', 'optimism', 'avalanche'],
},
},
required: [],
},
};
// ============================================================================
// Tool Implementation
// ============================================================================
/**
* Validate input parameters
*/
function validateInput(input: unknown): GetGasPricesInput {
if (input === null || input === undefined) {
return {};
}
if (typeof input !== 'object') {
throw new ValidationError('Input must be an object or empty');
}
const { chain } = input as Record<string, unknown>;
if (chain !== undefined) {
if (typeof chain !== 'string') {
throw new ValidationError('Chain must be a string');
}
const supportedChains = gasFetcher.getSupportedChains();
const normalizedChain = chain.toLowerCase().trim();
if (!supportedChains.includes(normalizedChain)) {
throw new ValidationError(
`Unsupported chain: ${chain}. Supported chains: ${supportedChains.join(', ')}`
);
}
return { chain: normalizedChain };
}
return {};
}
/**
* Get gas prices for one or all supported chains
*/
export async function getGasPrices(input: unknown): Promise<GetGasPricesOutput> {
const { chain } = validateInput(input);
const supportedChains = gasFetcher.getSupportedChains();
let gasPrices: GasPrice[];
if (chain) {
// Get gas price for specific chain
const gasPrice = await gasFetcher.getGasPrice(chain);
gasPrices = [gasPrice];
} else {
// Get gas prices for all chains
gasPrices = await gasFetcher.getAllGasPrices();
}
return {
gasPrices,
supportedChains,
timestamp: new Date().toISOString(),
};
}
