feat: json format option

Author: zoedsoupe

src/mcp.ts

@@ -18,25 +18,41 @@ async function handleProjectEvaluation({
   code,
   timeout,
   arguments: args,
+  json,
 }: ProjectEvalInputSchema): Promise<CallToolResult> {
   const result = await Tidewave.executeIsolated({ code, timeout, args });
 
   if (!result.success) {
+    if (json)
+      return {
+        content: [{ type: 'text', text: JSON.stringify(result) }],
+        isError: true,
+      };
+
     return {
       content: [
         {
           type: 'text',
-          // TODO: correctly format the exit
-          text: `Failed to evaluate code. Process exited with reason: ${JSON.stringify(result)}`,
+          text: `Failed to evaluate code. Process exited with reason: ${result.stderr}\n\n${result.result}`,
         },
       ],
       isError: true,
     };
   }
 
+  if (json)
+    return {
+      content: [{ type: 'text', text: JSON.stringify(result) }],
+      isError: false,
+    };
+
   return {
-    // TODO: correctly format success output
-    content: [{ type: 'text', text: JSON.stringify(result) }],
+    content: [
+      {
+        type: 'text',
+        text: `IO:\n\n${result.stdout}\n+${result.stderr}\n\nResult:${result.result}`,
+      },
+    ],
     isError: false,
   };
 }

src/tools.ts

@@ -30,13 +30,13 @@ const projectEvalDescription = `
 
         The current NodeJS version is: ${process.version}
 
-        Use this tool every time you need to evaluate Elixir code,
+        Use this tool every time you need to evaluate JavaScript/TypeScript code,
         including to test the behaviour of a function or to debug
         something. The tool also returns anything written to standard
-        output. DO NOT use shell tools to evaluate Elixir code.
+        output. DO NOT use shell tools to evaluate JavaScript/TypeScript code.
 
-        It also includes IEx helpers in the evaluation context.
-        For example, to get all functions in a module, call.
+        Imports are allowed only as the form of dynamic imports, e.g.:
+        import('node:path').then(path => {...});
 `;
 
 export const projectEvalInputSchema = z.object({
@@ -55,6 +55,11 @@ export const projectEvalInputSchema = z.object({
     .describe(
       'Optional. A timeout in milliseconds after which the execution stops if it did not finish yet.\nDefaults to 30000 (30 seconds).',
     ),
+  json: z
+    .boolean()
+    .optional()
+    .default(false)
+    .describe('Whether to return the result as JSON or not (string)'),
 });
 
 const referenceDescription = `Module path in format 'module:symbol[#method|.method]'. Supports local files, dependencies, and Node.js builtins.