feat: allow user override of hardcoded disallowed tools (#71)

* feat: allow user override of hardcoded disallowed tools

Allow users to override hardcoded disallowed tools (WebSearch, WebFetch) by including them in their allowed_tools configuration. This provides users with the ability to control tool access based on their security requirements.

Changes:
- Modified buildDisallowedToolsString() to accept allowedTools parameter
- Added logic to filter out hardcoded disallowed tools if present in allowed tools
- Updated function call site to pass allowedTools
- Added comprehensive test coverage for override behavior
- Maintains backward compatibility

Resolves #49

Co-authored-by: ashwin-ant <ashwin-ant@users.noreply.github.com>

* prettier

---------

Co-authored-by: claude[bot] <209825114+claude[bot]@users.noreply.github.com>
Co-authored-by: ashwin-ant <ashwin-ant@users.noreply.github.com>

test/create-prompt.test.ts

@@ -722,4 +722,51 @@ describe("buildDisallowedToolsString", () => {
     expect(parts).toContain("BadTool1");
     expect(parts).toContain("BadTool2");
   });
+
+  test("should remove hardcoded disallowed tools if they are in allowed tools", () => {
+    const customDisallowedTools = "BadTool1,BadTool2";
+    const allowedTools = "WebSearch,SomeOtherTool";
+    const result = buildDisallowedToolsString(
+      customDisallowedTools,
+      allowedTools,
+    );
+
+    // WebSearch should be removed from disallowed since it's in allowed
+    expect(result).not.toContain("WebSearch");
+
+    // WebFetch should still be disallowed since it's not in allowed
+    expect(result).toContain("WebFetch");
+
+    // Custom disallowed tools should still be present
+    expect(result).toContain("BadTool1");
+    expect(result).toContain("BadTool2");
+  });
+
+  test("should remove all hardcoded disallowed tools if they are all in allowed tools", () => {
+    const allowedTools = "WebSearch,WebFetch,SomeOtherTool";
+    const result = buildDisallowedToolsString(undefined, allowedTools);
+
+    // Both hardcoded disallowed tools should be removed
+    expect(result).not.toContain("WebSearch");
+    expect(result).not.toContain("WebFetch");
+
+    // Result should be empty since no custom disallowed tools provided
+    expect(result).toBe("");
+  });
+
+  test("should handle custom disallowed tools when all hardcoded tools are overridden", () => {
+    const customDisallowedTools = "BadTool1,BadTool2";
+    const allowedTools = "WebSearch,WebFetch";
+    const result = buildDisallowedToolsString(
+      customDisallowedTools,
+      allowedTools,
+    );
+
+    // Hardcoded tools should be removed
+    expect(result).not.toContain("WebSearch");
+    expect(result).not.toContain("WebFetch");
+
+    // Only custom disallowed tools should remain
+    expect(result).toBe("BadTool1,BadTool2");
+  });
 });