MCP Calc Tools

Instructions

Implementation Reference

• index.js:519-548 (handler)

  Core implementation of the option_greeks tool logic, calculating Delta, Gamma, Vega, Theta, and Rho using Black-Scholes formulas for call and put options.

  const optionGreeks = (S, K, T, r, sigma, optionType = 'call') => {
    try {
      const d1 = (Math.log(S / K) + (r + 0.5 * sigma * sigma) * T) / (sigma * Math.sqrt(T));
      const d2 = d1 - sigma * Math.sqrt(T);
  
      let delta, gamma, vega, theta, rho;
  
      if (optionType === 'call') {
        delta = normalCDF(d1);
        gamma = normalPDF(d1) / (S * sigma * Math.sqrt(T));
        vega = S * normalPDF(d1) * Math.sqrt(T);
        theta = -(S * normalPDF(d1) * sigma) / (2 * Math.sqrt(T)) - 
               r * K * Math.exp(-r * T) * normalCDF(d2);
        rho = K * T * Math.exp(-r * T) * normalCDF(d2);
      } else if (optionType === 'put') {
        delta = normalCDF(d1) - 1;
        gamma = normalPDF(d1) / (S * sigma * Math.sqrt(T));
        vega = S * normalPDF(d1) * Math.sqrt(T);
        theta = -(S * normalPDF(d1) * sigma) / (2 * Math.sqrt(T)) + 
               r * K * Math.exp(-r * T) * normalCDF(-d2);
        rho = -K * T * Math.exp(-r * T) * normalCDF(-d2);
      } else {
        throw new Error('Invalid option type. Must be "call" or "put".');
      }
  
      return { delta, gamma, vega, theta, rho };
    } catch (e) {
      return `Error: ${e.message}`;
    }
  };

• index.js:575-594 (schema)

  Input and output schema definitions for the option_greeks tool using Zod validation.

    inputSchema: z.object({
      S: z.number().describe('Current price of the asset'),
      K: z.number().describe('Strike price of the option'),
      T: z.number().describe('Time to expiration in years'),
      r: z.number().describe('Risk-free interest rate'),
      sigma: z.number().describe('Volatility of the asset'),
      optionType: z.enum(['call', 'put']).default('call')
        .describe('Option type: "call" or "put"')
    }),
    outputSchema: z.union([
      z.object({
        delta: z.number(),
        gamma: z.number(),
        vega: z.number(),
        theta: z.number(),
        rho: z.number()
      }),
      z.string()
    ]),
  },

• index.js:571-598 (registration)

  Registration of the 'option_greeks' tool with Genkit's ai.defineTool, linking schema and handler function.

  ai.defineTool(
    {
      name: 'option_greeks',
      description: 'Calculate the Greeks for a Black-Scholes option',
      inputSchema: z.object({
        S: z.number().describe('Current price of the asset'),
        K: z.number().describe('Strike price of the option'),
        T: z.number().describe('Time to expiration in years'),
        r: z.number().describe('Risk-free interest rate'),
        sigma: z.number().describe('Volatility of the asset'),
        optionType: z.enum(['call', 'put']).default('call')
          .describe('Option type: "call" or "put"')
      }),
      outputSchema: z.union([
        z.object({
          delta: z.number(),
          gamma: z.number(),
          vega: z.number(),
          theta: z.number(),
          rho: z.number()
        }),
        z.string()
      ]),
    },
    async ({ S, K, T, r, sigma, optionType }) => {
      return optionGreeks(S, K, T, r, sigma, optionType);
    }
  );