Reasoning Tool MCP Server

Official implementation of Anthropic's "reasoning" tool as an MCP server - Dramatically improve Claude's reasoning capabilities with structured thinking.

What is the Reasoning Tool?

This MCP server implements the exact "reasoning" tool that Anthropic introduced in their engineering blog post. The Reasoning Tool provides Claude with a dedicated space for structured reasoning during complex problem-solving tasks, enabling more thoughtful, accurate, and reliable responses.

Proven Performance Benefits

Anthropic's research demonstrates remarkable improvements when using the "reasoning" tool:

• 54% improvement in complex customer service tasks

• Significantly better adherence to detailed policies and guidelines

• Enhanced consistency across multiple trials of the same task

• Improved performance on software engineering benchmarks

• Minimal implementation overhead compared to other enhancement techniques

The "reasoning" tool excels where other approaches fall short:

• Better than extended thinking for cases requiring complex tool chains

• More effective than baseline prompting for policy-heavy scenarios

• Especially powerful when paired with optimized prompting

Quick Install

For Claude Desktop

For Cursor

How It Works

The "reasoning" tool implements the exact mechanism described in Anthropic's engineering blog. Unlike extended thinking (which happens before Claude starts responding), the "reasoning" tool allows Claude to pause and reflect during its response generation.

Key mechanism: The tool doesn't perform any external actions or retrieve new information - it simply provides Claude with a dedicated scratchpad to work through reasoning step-by-step, which dramatically improves performance on complex tasks.

When Claude uses the "reasoning" tool:

1. It pauses to organize thoughts before continuing a complex reasoning chain

2. It creates a structured approach to multi-step problems

3. It verifies policy compliance more thoroughly and consistently

4. It carefully analyzes tool outputs before deciding next steps

5. It maintains better context awareness across long interactions

When to Use the Reasoning Tool

The "reasoning" tool is especially valuable when:

1. Working with other MCP tools - Great for analyzing outputs from databases, filesystems, or APIs

2. Following complex policies - Perfect for customer service, legal, or compliance scenarios

3. Making sequential decisions - Ideal for workflows where later steps depend on earlier ones

4. Processing web search results - Helps Claude synthesize information from multiple sources

5. Solving coding challenges - Improves success rates on software engineering tasks

System Prompt for Optimal Results

Anthropic's research shows that combining the "reasoning" tool with optimized prompting delivers the strongest performance improvements. For best results, add the following optimized system prompt to your Claude interaction:

For Claude Desktop (Custom Instructions)

1. Go to Settings > Custom Instructions

2. Add the following system prompt:

For Cursor (Global Rules)

To add the Reasoning Tool as a Cursor Rule:

1. Open Cursor Settings

2. Navigate to General > Rules for AI

3. Add a new rule with the following content:

Manual Installation

If you prefer to run the server locally:

1. Clone the repository:

   git clone https://github.com/NexusX-MCP/reasoning-mcp-server.git cd reasoning-mcp-server

2. Install dependencies:

   npm install

3. Build and run:

   npm run build npm start

4. Configure Claude Desktop manually:

   • Find or create the configuration file:

     • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

     • Windows: %APPDATA%\Claude\claude_desktop_config.json

   • Add your server configuration:

   { "mcpServers": { "reasoning-tool": { "command": "node", "args": ["path/to/reasoning-mcp-server/dist/server.js"] } } }

License

MIT License