blocknative-mcp

Instructions

Implementation Reference

• src/blocknative_mcp/cli.py:99-139 (handler)

  The handler function for the 'estimate_gas_cost' tool, decorated with @mcp.tool() for registration. It validates inputs, fetches gas prices using the helper, selects the closest confidence prediction, calculates the total gas cost in Gwei and ETH, and returns a formatted string.
  @mcp.tool() async def estimate_gas_cost(gas_limit: int, confidence: int = 99, chain_id: int = 1, ctx: Optional[Context] = None) -> str: """ Estimate gas cost for a transaction based on gas limit, confidence level, and chain. Parameters: - gas_limit (int): The gas limit for the transaction (e.g., 21000 for a simple transfer). - confidence (int): The confidence level for gas price prediction (0-100). - chain_id (int): The ID of the blockchain network (e.g., 1 for Ethereum Mainnet). Default: 1. - ctx (Optional[Context]): The MCP context object. Default: None. """ if not (0 <= confidence <= 100): return "Error: Confidence must be between 0 and 100" if gas_limit <= 0: return "Error: Gas limit must be positive" data = await fetch_gas_prices(chain_id) if "error" in data: return data["error"] # Find the closest confidence level predictions = data["estimatedPrices"] closest_prediction = min( predictions, key=lambda p: abs(p.get("confidence", 0) - confidence), default={} ) if not closest_prediction: return "Error: No matching gas price prediction found" max_fee = closest_prediction.get("maxFeePerGas", 0) total_cost_gwei = max_fee * gas_limit total_cost_eth = total_cost_gwei / 1e9 # Convert Gwei to ETH return ( f"Estimated Gas Cost (Confidence {confidence}%, Chain ID {chain_id}):\n" f"- Gas Limit: {gas_limit}\n" f"- Max Fee Per Gas: {max_fee} Gwei\n" f"- Total Cost: {total_cost_gwei} Gwei ({total_cost_eth:.6f} ETH)" )
• src/blocknative_mcp/cli.py:19-48 (helper)

  Supporting helper function that fetches gas price data from the Blocknative API, extracts predictions and base fee, and handles errors. Used by the estimate_gas_cost handler.
  async def fetch_gas_prices(chain_id: int = 1) -> Dict: """Fetch gas price predictions from Blocknative API for a given chain.""" try: headers = {"Authorization": BLOCKNATIVE_API_KEY} if BLOCKNATIVE_API_KEY else {} async with httpx.AsyncClient() as client: response = await client.get( BLOCKNATIVE_GAS_API_URL, headers=headers, params={"chainid": chain_id} ) response.raise_for_status() data = response.json() # Extract relevant fields from the response block_prices = data.get("blockPrices", []) if not block_prices: return {"error": "No block prices found in API response"} # Use the first block's data first_block = block_prices[0] return { "baseFeePerGas": first_block.get("baseFeePerGas", 0), "estimatedPrices": first_block.get("estimatedPrices", []), "unit": data.get("unit", "gwei"), "system": data.get("system", "unknown"), "network": data.get("network", "unknown") } except httpx.HTTPError as e: return {"error": f"Failed to fetch gas prices for chain ID {chain_id}: {str(e)}"}
• src/blocknative_mcp/cli.py:100-109 (schema)

  Function signature with type annotations and docstring defining the input parameters and return type, serving as the tool schema.
  async def estimate_gas_cost(gas_limit: int, confidence: int = 99, chain_id: int = 1, ctx: Optional[Context] = None) -> str: """ Estimate gas cost for a transaction based on gas limit, confidence level, and chain. Parameters: - gas_limit (int): The gas limit for the transaction (e.g., 21000 for a simple transfer). - confidence (int): The confidence level for gas price prediction (0-100). - chain_id (int): The ID of the blockchain network (e.g., 1 for Ethereum Mainnet). Default: 1. - ctx (Optional[Context]): The MCP context object. Default: None. """
• src/blocknative_mcp/cli.py:99-99 (registration)

  The @mcp.tool() decorator registers the estimate_gas_cost function as an MCP tool.
  @mcp.tool()