feat(plugin-code-execution): enhance schema validation for code execution and improve error messages

Author: yaonyan

packages/core/src/executors/agentic/agentic-executor.ts

@@ -104,15 +104,16 @@ export class AgenticExecutor {
 
         const result: CallToolResult = { content: [] };
         this.appendToolSchemas(result, definitionsOf, hasDefinitions);
-        
+
         // If no schemas were added (all requested tools already in hasDefinitions), give feedback
         if (result.content.length === 0 && definitionsOf.length > 0) {
           result.content.push({
             type: "text",
-            text: `All requested tool schemas are already in hasDefinitions. You can now call a tool using "${this.USE_TOOL_KEY}".`,
+            text:
+              `All requested tool schemas are already in hasDefinitions. You can now call a tool using "${this.USE_TOOL_KEY}".`,
           });
         }
-        
+
         return result;
       }
 
@@ -244,7 +245,9 @@ export class AgenticExecutor {
         content: [
           {
             type: "text",
-            text: `Tool "${useTool}" not found. Available tools: ${this.allToolNames.join(", ")}.`,
+            text: `Tool "${useTool}" not found. Available tools: ${
+              this.allToolNames.join(", ")
+            }.`,
           },
         ],
         isError: true,

packages/core/src/factories/args-def-factory.ts

@@ -109,13 +109,21 @@ Workflow step definitions - provide ONLY on initial call.
       enum: Object.values(DECISION_OPTIONS),
       description:
         `**Step control: \`${DECISION_OPTIONS.PROCEED}\` = next step, \`${DECISION_OPTIONS.RETRY}\` = retry/repeat current, \`${DECISION_OPTIONS.COMPLETE}\` = finish workflow**`,
+      errorMessage: {
+        enum: `Invalid decision. Must be one of: ${
+          Object.values(DECISION_OPTIONS).join(", ")
+        }.`,
+      },
     }),
 
     action: (): JSONSchema => ({
       type: "string",
       description: "Define the current workflow action to be performed",
       enum: allToolNames,
       required: ["action"],
+      errorMessage: {
+        enum: `Invalid action. Must be one of: ${allToolNames.join(", ")}.`,
+      },
     }),
 
     forTool: function (): JSONSchema {
@@ -162,6 +170,14 @@ Workflow step definitions - provide ONLY on initial call.
           },
         },
         required: ["userRequest", "context"],
+        errorMessage: {
+          required: {
+            userRequest:
+              "Missing required field 'userRequest'. Please provide a clear task description.",
+            context:
+              "Missing required field 'context'. Please provide relevant context (e.g., current working directory).",
+          },
+        },
       };
     },
 
@@ -183,7 +199,8 @@ Workflow step definitions - provide ONLY on initial call.
                 required: [toolName],
                 errorMessage: {
                   required: {
-                    [toolName]: `Tool "${toolName}" is selected but its parameters are missing. Please provide "${toolName}": { ...parameters }.`,
+                    [toolName]:
+                      `Tool "${toolName}" is selected but its parameters are missing. Please provide "${toolName}": { ...parameters }.`,
                   },
                 },
               },
@@ -205,7 +222,9 @@ Workflow step definitions - provide ONLY on initial call.
           enum: allToolNames,
           description: useToolDescription,
           errorMessage: {
-            enum: `Invalid tool name. Available tools: ${allToolNames.join(", ")}.`,
+            enum: `Invalid tool name. Available tools: ${
+              allToolNames.join(", ")
+            }.`,
           },
         },
         hasDefinitions: {
@@ -243,7 +262,10 @@ Workflow step definitions - provide ONLY on initial call.
           required: [USE_TOOL_KEY],
           errorMessage: {
             required: {
-              [USE_TOOL_KEY]: `No tool selected. Please specify "${USE_TOOL_KEY}" to select one of: ${allToolNames.join(", ")}. Or use "definitionsOf" with tool names to get their schemas first.`,
+              [USE_TOOL_KEY]:
+                `No tool selected. Please specify "${USE_TOOL_KEY}" to select one of: ${
+                  allToolNames.join(", ")
+                }. Or use "definitionsOf" with tool names to get their schemas first.`,
             },
           },
         };

packages/core/src/utils/schema-validator.ts

@@ -19,7 +19,7 @@ export function validateSchema(
   const validate = ajv.compile(schema);
   if (!validate(args)) {
     const errors = validate.errors!;
-    
+
     // If there are custom errorMessage errors, use only those
     const customErrors = errors.filter((err) => err.keyword === "errorMessage");
     if (customErrors.length > 0) {
@@ -29,7 +29,7 @@ export function validateSchema(
         error: messages.join("; "),
       };
     }
-    
+
     // Fallback to human-readable error formatting
     const aggregateError = new AggregateAjvError(errors);
     return {

packages/plugin-code-execution/deno.json

@@ -1,6 +1,6 @@
 {
   "name": "@mcpc/plugin-code-execution",
-  "version": "0.0.6",
+  "version": "0.0.7",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/mcpc-tech/mcpc.git"

packages/plugin-code-execution/src/plugin.ts

@@ -63,6 +63,32 @@ export function createCodeExecutionPlugin(
               "Tool names whose schemas were already provided in this conversation. List all tools you have schemas for to avoid duplicate schema requests",
           },
         },
+        // Conditional validation: if code is provided, hasDefinitions must be non-empty
+        if: {
+          properties: { code: { type: "string", minLength: 1 } },
+          required: ["code"],
+        },
+        then: {
+          properties: {
+            hasDefinitions: { type: "array", minItems: 1 },
+          },
+          required: ["hasDefinitions"],
+          errorMessage: {
+            required: {
+              hasDefinitions:
+                "When executing code, you must provide 'hasDefinitions' with tool schemas you have. First request schemas using 'definitionsOf'.",
+            },
+          },
+        },
+        // If no code, must have definitionsOf
+        else: {
+          anyOf: [
+            { required: ["definitionsOf"] },
+            { required: ["code"] },
+          ],
+          errorMessage:
+            "Provide either 'code' to execute or 'definitionsOf' to request tool schemas.",
+        },
       } as const;
 
       // Register tool with enhanced description
@@ -76,8 +102,8 @@ export function createCodeExecutionPlugin(
           const hasDefinitions = (args.hasDefinitions as string[]) || [];
           const contentParts: CallToolResult["content"] = [];
 
-          // Execute code
-          if (code && hasDefinitions.length > 0) {
+          // Execute code (schema validation ensures hasDefinitions is present when code is provided)
+          if (code) {
             if (!executor) throw new Error("Sandbox not initialized");
 
             const result = await executor.executeCode(code, hasDefinitions);
@@ -116,8 +142,17 @@ export function createCodeExecutionPlugin(
             }
           }
 
-          const text = contentParts.map((p) => p.text).join("\n") ||
-            "No output generated, use console.log() to log output";
+          // Generate appropriate response message
+          let text: string;
+          if (contentParts.length > 0) {
+            text = contentParts.map((p) => p.text).join("\n");
+          } else if (definitionsOf.length > 0) {
+            // All requested schemas already in hasDefinitions
+            text =
+              "All requested tool schemas are already available. You can now execute code using 'code' parameter.";
+          } else {
+            text = "no output generated, use console.log() to log output";
+          }
 
           return { content: [{ type: "text", text }] };
         },