Sequential Thinking MCP Server - Streamable HTTP Implementation

An MCP server that provides a powerful sequential thinking tool for complex problem-solving through thoughts.

This server enables AI assistants to work through problems step-by-step, with the ability to revise, branch, and explore alternative approaches as understanding deepens.

Features

• Dynamic Thought Process: Adjust the number of thoughts as you progress

• Revision Capability: Question and revise previous thoughts

• Branching Logic: Explore alternative approaches

• Flexible Planning: Add more thoughts even after reaching initial estimates

• Context Preservation: Maintain context across multiple thinking steps

Getting Started

To get started with this server, clone the repository and install the necessary dependencies.

Usage

Streamable HTTP Transport

The server uses the modern Streamable HTTP transport protocol for communication. Start the server:

The server will start on http://127.0.0.1:3000 by default. You can change the port using the PORT environment variable:

Endpoints

• MCP Endpoint: POST/GET/DELETE http://127.0.0.1:3000/mcp - Main MCP communication endpoint

  • POST - Send messages to the server (initialize, tool calls, etc.)

  • GET - Establish SSE stream for server-to-client notifications

  • DELETE - Terminate session

• Health Check: GET http://127.0.0.1:3000/health - Check server status and active sessions

• Test Interface: GET http://127.0.0.1:3000/ - Browser-based test interface

Transport Features

The Streamable HTTP transport provides several advantages:

• Session-Based State: Manages state for each client session in memory. The core server is long-running and can be scaled with sticky sessions.

• Flexible Streaming: Server can upgrade any response to SSE for streaming

• Infrastructure Compatible: Works with standard HTTP middleware and proxies

• Resumable Connections: Support for connection resumption

• Automatic Session Cleanup: Inactive sessions and their associated data are automatically cleared after 1 hour to conserve resources.

Security

The implementation includes security measures:

• Origin header validation to prevent DNS rebinding attacks

• Server binds only to localhost (127.0.0.1)

• CORS headers are properly configured

• Session IDs are cryptographically secure

• Privacy by Design: No sensitive tool inputs or outputs are logged to the console.

Adding to Cursor

To use this server with Cursor, add the following to your Cursor configuration:

Running with Docker

You can also run the server in a containerized environment using Docker for easier deployment and isolation.

1. Build the Docker image:

   docker build -t mcp-server-sequential-thinking .

2. Run the Docker container:

   docker run -p 3000:3000 mcp-server-sequential-thinking

The server will be accessible at http://127.0.0.1:3000.

Available Tool

sequentialthinking

A detailed tool for dynamic and reflective problem-solving through thoughts.

When to use:

• Breaking down complex problems into steps

• Planning and design with room for revision

• Analysis that might need course correction

• Problems where the full scope might not be clear initially

• Multi-step solutions requiring context preservation

Parameters:

• thought (string, required): Your current thinking step

• nextThoughtNeeded (boolean, required): Whether another thought step is needed

• thoughtNumber (integer, required): Current thought number

• totalThoughts (integer, required): Estimated total thoughts needed

• isRevision (boolean, optional): Whether this revises previous thinking

• revisesThought (integer, optional): Which thought is being reconsidered

• branchFromThought (integer, optional): Branching point thought number

• branchId (string, optional): Branch identifier

• needsMoreThoughts (boolean, optional): If more thoughts are needed

License

MIT