MCP Toolkit: Fixing Missing Required Fields In Test Settings

by Alex Johnson 61 views

This article addresses a critical bug within the Test Settings section of the Playwright and GitHub MCP (Meta Configuration Platform) toolkits. Currently, users can initiate tool execution even when certain fields mandated by the ArgsSchema are left unfilled. This oversight leads to validation errors and hinders the usability of the MCP toolkits. Let's dive into the details and explore the necessary fixes.

Understanding the Problem: ArgsSchema Validation Errors

The root cause of this issue lies in the discrepancy between the ArgsSchema requirements and the UI representation within the Test Settings. Specifically, several fields that are required by the ArgsSchema are not designated as such in the user interface. This means users can inadvertently click the Run Tool button without providing all the necessary input values. Consequently, the tool execution falters and throws ArgsSchema validation errors, creating a frustrating experience for users. Imagine setting up a complex test scenario, only to have it fail because a seemingly optional field was actually mandatory behind the scenes. This inconsistency undermines the reliability and efficiency of the MCP toolkits, making it crucial to address this bug promptly. The goal is to ensure that the UI accurately reflects the ArgsSchema requirements, preventing users from submitting incomplete or invalid requests. This will not only streamline the testing process but also enhance the overall user experience by providing clear guidance and preventing unexpected errors.

Steps to Reproduce the Bug

To better illustrate the bug, here are the steps to reproduce it:

  1. Create an MCP toolkit: Begin by creating either a Playwright or GitHub MCP toolkit and establish a connection to MCP.
  2. Open Test Settings: Navigate to the Test Settings section within the toolkit.
  3. Select a Tool: Choose a tool from the available list (specific tools are detailed below).
  4. Fill in Fields: Populate only the fields that are explicitly indicated as required in the UI (those marked with an asterisk *).
  5. Run the Tool: Initiate the tool execution.

Observe:

  • The Run Tool button is enabled even though not all schema-required fields were filled.
  • ArgsSchema validation errors occur because required values are missing.

Expected vs. Actual Result

Expected Result:

  • The UI should accurately display all schema-required fields as required (marked with *).
  • The Run Tool button should only be enabled when all required fields contain valid input.
  • Tool execution in the Test Settings should not produce ArgsSchema validation errors.

Actual Result:

  • ArgsSchema validation errors occur because empty fields ("" or undefined values) are submitted.
  • The UI does not protect users from submitting invalid requests.

Toolkit-Specific Issues and Resolutions

Let's examine the specific toolkits affected and outline the necessary corrections to resolve this bug. We'll focus on identifying the missing required fields and ensuring they are properly marked in the UI. This will provide a clear roadmap for developers to address the inconsistencies and improve the overall functionality of the MCP toolkits. By meticulously addressing each toolkit's specific issues, we can create a more robust and user-friendly testing environment. This will ultimately save time and effort for users, while also ensuring the accuracy and reliability of test results.

1) Playwright MCP Toolkit

For the Playwright MCP Toolkit, the following fields need to be marked as required in the Test Settings UI to prevent invalid executions:

  • browser_click → button
  • browser_tabs → index
  • browser_wait_for → time

2) GitHub MCP Toolkit

For the GitHub MCP Toolkit, the following fields need to be marked as required in the Test Settings UI to prevent invalid executions:

  • list_commits → page, perPage
  • list_issues → direction, page, per_page, sort, state, since
  • list_pull_requests → state, sort, direction, per_page, page
  • merge_pull_request → merge_request
  • search_code → order, page, per_page
  • search_issues → order, page, per_page, sort
  • search_repositories → page, perPage
  • search_users → order, page, per_page, sort
  • update_issue → state, title

Special Cases (GitHub MCP Toolkit):

  • create_issue → milestone is a required field in ArgsSchema. It would be better to make this field optional. This may be a BE issue. If that is not possible, then mark it as required in the UI.
  • update_issue → milestone is a required field in ArgsSchema. It would be better to make this field optional. This may be a BE issue. If that is not possible, then mark it as required in the UI.
  • create_pull_request_review → commit_id always appears in the request even if the user does not input any value. If possible, remove this field from the request when empty. If not possible, then mark it as required.

The GitHub MCP Toolkit presents some unique challenges. The milestone field in both create_issue and update_issue is currently required by the ArgsSchema, but it would be more user-friendly to make it optional. This potential backend issue needs to be investigated. If modifying the backend is not feasible, the milestone field should be marked as required in the UI to maintain consistency. Additionally, the commit_id field in create_pull_request_review always appears in the request, even when no value is provided. Ideally, this field should be removed from the request when empty. If that's not possible, it should also be marked as required in the UI. Addressing these special cases will significantly improve the usability and intuitiveness of the GitHub MCP Toolkit.

Visual Examples of ArgsSchema Errors

To provide clarity, here are some visual examples of the ArgsSchema errors that occur due to the missing required fields:

Image Image Image

These images clearly demonstrate the ArgsSchema validation errors that users encounter when required fields are left blank. By rectifying these issues, the MCP toolkits can become more reliable and user-friendly. Resolving this bug will improve the overall experience for developers and testers using the platform, reducing frustration and improving efficiency.

Conclusion: Enhancing MCP Toolkit Usability

In conclusion, resolving the issue of missing required fields in the Test Settings section of the MCP toolkits is crucial for enhancing usability and preventing validation errors. By accurately reflecting the ArgsSchema requirements in the UI and addressing the special cases within the GitHub MCP Toolkit, we can create a more robust and user-friendly testing environment. This will not only save time and effort for users but also ensure the accuracy and reliability of test results. The goal is to empower users with clear guidance and prevent unexpected errors, ultimately streamlining the testing process and improving the overall user experience.

For more information on schema validation and best practices, visit the JSON Schema website. This external resource provides comprehensive documentation and examples that can be helpful in understanding and implementing proper schema validation techniques.