diff --git a/packages/mcp/src/tools/validate.ts b/packages/mcp/src/tools/validate.ts
index 87475d9..a02dd63 100644
--- a/packages/mcp/src/tools/validate.ts
+++ b/packages/mcp/src/tools/validate.ts
@@ -3,6 +3,11 @@ import type { ComponentRegistry } from "../registry.js";
 interface ValidateInput { component: string; schema?: string; props?: Record<string, unknown>; parts?: string[]; }
 interface ValidateResult { valid: boolean; errors: string[]; }
 
+interface ZodParseIssue { message: string; path: (string | number)[]; }
+interface ZodParseError { issues: ZodParseIssue[]; }
+interface ZodParseResult { success: boolean; error?: ZodParseError; }
+interface ZodSchema { safeParse(data: unknown): ZodParseResult; }
+
 /** Validates props against schema and/or checks required parts are present. */
 export function handleValidate(registry: ComponentRegistry, input: ValidateInput): ValidateResult {
   const comp = registry.getComponent(input.component);
@@ -16,8 +21,7 @@ export function handleValidate(registry: ComponentRegistry, input: ValidateInput
     if (!schema) {
       errors.push(`Schema "${input.schema}" not found on ${comp.meta.name}`);
     } else {
-      // schema is a Zod schema — call safeParse
-      const zSchema = schema as { safeParse: (data: unknown) => { success: boolean; error?: { issues: Array<{ message: string; path: (string | number)[] }> } } };
+      const zSchema = schema as ZodSchema;
       const result = zSchema.safeParse(input.props);
       if (!result.success && result.error) {
         for (const issue of result.error.issues) {
diff --git a/packages/mcp/tests/tools/validate.test.ts b/packages/mcp/tests/tools/validate.test.ts
new file mode 100644
index 0000000..6288394
--- /dev/null
+++ b/packages/mcp/tests/tools/validate.test.ts
@@ -0,0 +1,43 @@
+import { describe, it, expect } from "vitest";
+import { handleValidate } from "../../src/tools/validate.js";
+import { ComponentRegistry } from "../../src/registry.js";
+
+describe("pettyui.validate", () => {
+  const registry = new ComponentRegistry();
+
+  it("validates correct props", () => {
+    const result = handleValidate(registry, { component: "Dialog", schema: "dialogRoot", props: { open: true, modal: false } });
+    expect(result.valid).toBe(true);
+    expect(result.errors).toHaveLength(0);
+  });
+
+  it("rejects invalid props", () => {
+    const result = handleValidate(registry, { component: "Dialog", schema: "dialogRoot", props: { open: "yes" } });
+    expect(result.valid).toBe(false);
+    expect(result.errors.length).toBeGreaterThan(0);
+  });
+
+  it("validates empty props", () => {
+    const result = handleValidate(registry, { component: "Dialog", schema: "dialogRoot", props: {} });
+    expect(result.valid).toBe(true);
+    expect(result.errors).toHaveLength(0);
+  });
+
+  it("checks required parts present — missing Title", () => {
+    const result = handleValidate(registry, { component: "Dialog", parts: ["Root", "Content"] });
+    expect(result.valid).toBe(false);
+    expect(result.errors).toContain("Missing required part: Title");
+  });
+
+  it("passes when all required parts provided", () => {
+    const result = handleValidate(registry, { component: "Dialog", parts: ["Root", "Content", "Title"] });
+    expect(result.valid).toBe(true);
+    expect(result.errors).toHaveLength(0);
+  });
+
+  it("returns error for unknown component", () => {
+    const result = handleValidate(registry, { component: "FakeComponent" });
+    expect(result.valid).toBe(false);
+    expect(result.errors).toContain('Component "FakeComponent" not found');
+  });
+});