crypto-pegmon-mcp

Instructions

Fetch historical price data for a USD-pegged stablecoin and return as a Markdown table.

Args:
    coin (str): The symbol of the stablecoin (e.g., 'usdt', 'usdc', 'dai').
    days (int, optional): Number of days for historical data. Defaults to 7.

Returns:
    str: A Markdown table with date, price, and deviation.

Implementation Reference

• main.py:130-160 (handler)

  The handler function for the 'get_historical_data' tool. It fetches historical price data from CoinGecko API, computes deviations from $1 peg, and returns a Markdown table. Registered via @mcp.tool() decorator.

  @mcp.tool()
  def get_historical_data(coin: str, days: int = 7) -> str:
      """
      Fetch historical price data for a USD-pegged stablecoin and return as a Markdown table.
  
      Args:
          coin (str): The symbol of the stablecoin (e.g., 'usdt', 'usdc', 'dai').
          days (int, optional): Number of days for historical data. Defaults to 7.
  
      Returns:
          str: A Markdown table with date, price, and deviation.
      """
      if coin.lower() not in STABLECOINS:
          return f"Error: Unsupported stablecoin. Choose from {list(STABLECOINS.keys())}"
      
      coin_id = STABLECOINS[coin.lower()]["id"]
      try:
          # Fetch historical data for the specified number of days
          data = cg.get_coin_market_chart_by_id(id=coin_id, vs_currency="usd", days=days)
          prices = [(datetime.fromtimestamp(item[0]/1000).strftime("%Y-%m-%d"), item[1]) 
                    for item in data["prices"]]
          
          # Create DataFrame for prices and deviations
          df = pd.DataFrame(prices, columns=["Date", "Price"])
          df["Deviation (%)"] = (df["Price"] - 1.0) * 100
          
          # Convert to Markdown table
          markdown_table = df.to_markdown(index=False, floatfmt=".4f")
          return f"**{coin.upper()} Historical Data (Last {days} Days)**:\n\n{markdown_table}"
      except Exception as e:
          return f"Error fetching historical data for {coin}: {str(e)}"

• main.py:15-84 (helper)

  Global dictionary mapping stablecoin symbols to their CoinGecko IDs and descriptions. Used by get_historical_data for validation and ID lookup.

  STABLECOINS = {
      "usdt": {
          "id": "tether",
          "description": "Tether's USD-pegged stablecoin, centrally issued."
      },
      "usdc": {
          "id": "usd-coin",
          "description": "Circle's USD-backed stablecoin, widely used in DeFi."
      },
      "dai": {
          "id": "dai",
          "description": "Decentralized stablecoin by MakerDAO, collateralized by crypto."
      },
      "busd": {
          "id": "binance-usd",
          "description": "Binance's USD-pegged stablecoin, centrally managed."
      },
      "tusd": {
          "id": "true-usd",
          "description": "TrueUSD, a USD-backed stablecoin by TrustToken."
      },
      "frax": {
          "id": "frax",
          "description": "Fractional-algorithmic USD stablecoin by Frax Finance."
      },
      "usdd": {
          "id": "usdd",
          "description": "TRON's USD-pegged stablecoin, centrally issued."
      },
      "usds": {
          "id": "usds",
          "description": "USD-pegged stablecoin, focused on stability."
      },
      "susds": {
          "id": "susds",
          "description": "Staked USDS, yield-bearing stablecoin."
      },
      "eusde": {
          "id": "ethena-staked-usde",
          "description": "Ethena's staked USD stablecoin, yield-bearing."
      },
      "usdy": {
          "id": "ondo-us-dollar-yield",
          "description": "Ondo's USD yield stablecoin, designed for returns."
      },
      "pyusd": {
          "id": "paypal-usd",
          "description": "PayPal's USD-pegged stablecoin for payments."
      },
      "gusd": {
          "id": "gemini-dollar",
          "description": "Gemini Dollar, USD-backed by Gemini Trust."
      },
      "usdp": {
          "id": "paxos-standard",
          "description": "Paxos Standard, a regulated USD stablecoin."
      },
      "aave-usdc": {
          "id": "aave-usdc",
          "description": "Aave's USD-pegged stablecoin for lending."
      },
      "curve-usd": {
          "id": "curve-usd",
          "description": "Curve Finance's USD stablecoin for DeFi pools."
      },
      "mim": {
          "id": "magic-internet-money",
          "description": "Magic Internet Money, a decentralized USD stablecoin."
      }
  }