chainlist-mcp

Instructions

Implementation Reference

• main.py:83-110 (handler)

  The complete handler function for the 'getChainsByKeyword' tool. Registered via @mcp.tool() decorator. Includes input schema in docstring (keyword: str, optional limit: int=5), fetches cached chain data, filters chains by case-insensitive keyword match using regex, limits results, formats output as Markdown using helper, or returns error message.
  @mcp.tool() async def getChainsByKeyword(keyword: str, limit: int = 5) -> str: """ Retrieve information about blockchains matching a keyword (case-insensitive partial match), returned as Markdown. **Parameters**: - `keyword` (string): The keyword or partial name of the blockchain to search for (e.g., 'eth' for Ethereum). - `limit` (integer, optional): Maximum number of matching chains to return (default: 5). **Returns**: - A Markdown-formatted string listing up to `limit` matching chains with their details (Name, Chain ID, Native Currency, TVL, RPC Endpoints, Explorers) or an error message if no chains are found. """ chains = await fetch_chain_data() pattern = re.escape(keyword.strip()) matches: List[Dict[str, Any]] = [] for chain in chains: chain_name = chain.get("name", "") if re.search(pattern, chain_name, re.IGNORECASE): matches.append(chain) if matches: output = "**Matching Chains**\n\n" # Apply limit to matches for i, chain in enumerate(matches[:limit], 1): output += f"### Chain {i}\n{format_chain_as_markdown(chain)}\n" return output return f"**Error**: No chains found matching keyword '{keyword}'"
• main.py:14-22 (helper)

  Helper function to fetch and cache the list of all chains from the Chainlist API. Called by the getChainsByKeyword handler.
  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 dictionary into a detailed Markdown string with tables for RPC endpoints and explorers. Used by getChainsByKeyword to format each matching chain.
  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} """