Update tool defs

Author: Jesus Terrazas

mcp/MockTools/MockToolModels.cs

@@ -10,7 +10,7 @@ public class MockToolDefinition
     [JsonPropertyName("inputSchema")] public object InputSchema { get; set; } = new { type = "object", properties = new { }, required = Array.Empty<string>() };
 
     // Response behavior
-    [JsonPropertyName("responseTemplate")] public object ResponseTemplate { get; set; } = new { };
+    [JsonPropertyName("responseTemplate")] public string ResponseTemplate { get; set; } = "Mock response from {{name}}";
     [JsonPropertyName("delayMs")] public int DelayMs { get; set; } = 0;
     [JsonPropertyName("errorRate")] public double ErrorRate { get; set; } = 0.0; // 0-1
     [JsonPropertyName("statusCode")] public int StatusCode { get; set; } = 200;