chainlist-mcp

Instructions

Implementation Reference

• main.py:67-81 (handler)

  The handler function for the 'getChainById' tool. It is decorated with @mcp.tool() which registers it. Fetches chain data, searches for the chain by ID, formats details as Markdown or returns error.
  async def getChainById(chain_id: int) -> str: """ Retrieve information about a blockchain by its chain ID, returned as Markdown. **Parameters**: - `chain_id` (integer): The unique identifier of the blockchain (e.g., 1 for Ethereum Mainnet). **Returns**: - A Markdown-formatted string containing the chain's details (Name, Chain ID, Native Currency, TVL, RPC Endpoints, Explorers) or an error message if no chain is found. """ chains = await fetch_chain_data() for chain in chains: if chain.get("chainId") == chain_id: return format_chain_as_markdown(chain) return f"**Error**: No chain found with ID {chain_id}"
• main.py:14-22 (helper)

  Helper function to fetch and cache the chain data from the Chainlist API, used by getChainById.
  async def fetch_chain_data() -> list[Dict[str, Any]]: """Fetch and cache chain data from Chainlist API.""" global chain_data if chain_data is None: async with httpx.AsyncClient() as client: response = await client.get("https://chainlist.org/rpcs.json") response.raise_for_status() chain_data = response.json() return chain_data
• main.py:24-64 (helper)

  Helper function to format a single chain's details into a Markdown string with tables for RPCs and explorers, called by getChainById.
  def format_chain_as_markdown(chain: Dict[str, Any]) -> str: """ Format a single chain's details as Markdown, extracting specified fields with RPC and Explorers as tables. """ # Extract required fields name = chain.get('name', 'N/A') chain_id = chain.get('chainId', 'N/A') native_currency = chain.get('nativeCurrency', {}) tvl = chain.get('tvl', 'N/A') rpc_list = chain.get('rpc', []) explorers_list = chain.get('explorers', []) # Format native currency currency_info = f"{native_currency.get('name', 'N/A')} ({native_currency.get('symbol', 'N/A')}, {native_currency.get('decimals', 'N/A')} decimals)" if native_currency else 'N/A' # Format RPC list as a table rpc_data = [[rpc.get('url', 'N/A'), rpc.get('tracking', 'N/A')] for rpc in rpc_list] rpc_output = "**RPC Endpoints**:\n" if rpc_data: rpc_output += tabulate(rpc_data, headers=["URL", "Tracking"], tablefmt="pipe") else: rpc_output += "None" # Format explorers list as a table explorers_data = [[explorer.get('name', 'N/A'), explorer.get('url', 'N/A'), explorer.get('standard', 'N/A')] for explorer in explorers_list] explorers_output = "**Explorers**:\n" if explorers_data: explorers_output += tabulate(explorers_data, headers=["Name", "URL", "Standard"], tablefmt="pipe") else: explorers_output += "None" # Combine all fields return f"""**Chain Details** - **Name**: {name} - **Chain ID**: {chain_id} - **Native Currency**: {currency_info} - **TVL**: {tvl} {rpc_output} {explorers_output} """
• main.py:67-67 (registration)

  The @mcp.tool() decorator registers the getChainById function as an MCP tool.
  async def getChainById(chain_id: int) -> str: