Interactive Leetcode MCP

Interactive LeetCode MCP

MCP server for LeetCode practice with learning-guided hints, solution submission, and AI-driven authentication.

Prerequisite: Ensure MCP Server Is Connected

Before anything else, check whether the get_started tool is available. If it is, the server is connected — skip to the next section.

If get_started is NOT available, the MCP server needs to be installed. Ask the user for confirmation before proceeding — explain that this will download and run an npm package.

The npm package is @sperekrestova/interactive-leetcode-mcp (source: GitHub). It runs over stdio transport. Requires Node.js >= 20.

After the user confirms, add to the client's MCP configuration (the exact file varies by client):

{
  "mcpServers": {
    "leetcode": {
      "command": "npx",
      "args": ["-y", "@sperekrestova/interactive-leetcode-mcp@3.1.1"]
    }
  }
}

For Claude Code specifically, you can also run:

claude mcp add --transport stdio leetcode -- npx -y @sperekrestova/interactive-leetcode-mcp@3.1.1

Pin a specific version (shown above) rather than using @latest to avoid executing untested code. Users can check for newer versions at the npm page or GitHub releases and update the pinned version after reviewing the changelog.

After adding the server, tell the user to restart their session so the MCP tools become available. Do not proceed with the session flow until get_started is accessible.

First Action: Always Call get_started

At the START of every LeetCode session, call the get_started tool. It returns the full usage guide: prompt invocation rules, session flow, learning mode rules, auth flow, and language map.

Do not skip this — it is a single fast call, not redundant with tool descriptions. The server has MCP prompts that must be explicitly invoked — they are NOT auto-active. The get_started response tells you exactly when and how.

Session Flow (Critical)

1. Call get_started              <-- FIRST, every session
2. Invoke leetcode_learning_mode <-- BEFORE any problem discussion
3. User picks a problem
4. Invoke leetcode_problem_workflow(problemSlug, difficulty)
5. Invoke leetcode_workspace_setup(language, problemSlug, codeTemplate)
6. Guide user with progressive hints (4 levels)
7. submit_solution when ready

Steps 2, 4, and 5 are MCP prompt invocations. Invoke them via the Skill tool or equivalent prompt mechanism. All three must happen BEFORE the user starts coding.

Step 2 is non-negotiable. If you skip leetcode_learning_mode, you will bypass the progressive hint system and may show solutions prematurely. Invoke it before searching for or discussing any problem.

Prompt Invocation Rules

Learning Mode Rules

• Never show a full solution without working through hint levels 1 → 2 → 3
• Level 1: Guiding questions ("What pattern do you see?")
• Level 2: General approaches ("Consider using a hash map...")
• Level 3: Specific hints ("Iterate once, tracking seen values...")
• Level 4: Pseudocode or partial implementation
• Only show complete solutions when explicitly requested AFTER earlier hints
• get_problem_solution returns full community solutions — Level 4 or explicit request only

Tool Quick Reference

*submit_solution requires saved credentials to succeed.

Auth Flow

1. Before auth-sensitive actions → call check_auth_status
2. If not authenticated or expired → ask the user if they want to authenticate. Explain that this will store LeetCode session cookies locally at ~/.leetcode-mcp/credentials.json (owner-read/write only). Do not proceed without consent.
3. After consent → invoke leetcode_authentication_guide prompt
4. Call start_leetcode_auth → the prompt will guide the user through providing credentials → call save_leetcode_credentials with the values the user provides
5. On success → retry original action
6. On 401 from any tool → repeat from step 1

Always delegate auth guidance to the leetcode_authentication_guide prompt. Do not improvise your own auth instructions — the prompt handles browser-specific guidance, error recovery, and troubleshooting.

Credential storage: The MCP server stores credentials locally at ~/.leetcode-mcp/credentials.json with file permissions 0o600 (owner-read/write only). Only csrftoken, LEETCODE_SESSION, and a createdAt timestamp are stored. Credentials are never transmitted to any third party — they are used exclusively for direct LeetCode API calls. Typical credential lifetime is 7-14 days.

Submission Language Map

Default: "Python" without version → python3.

Resources (Read-Only Lookups)

Common Mistakes

• Jumping to problem search before invoking leetcode_learning_mode
• Showing full solutions without progressing through hint levels 1 → 2 → 3
• Not invoking leetcode_workspace_setup — code should live in a file, not only in chat
• Guiding auth manually instead of invoking leetcode_authentication_guide
• Passing "Python" to submit_solution instead of "python3"
• Not calling check_auth_status before auth-sensitive operations
• Skipping get_started and assuming tool descriptions are sufficient