This MCP server implements Anthropic's "Think Tool" technique, allowing Claude to break down complex problems and enhance its reasoning capabilities. It's a simple but effective prompt engineering approach that gives Claude a space to organize thoughts and show its work.
Before installing the MCP Think Tool, ensure you have:
Clone the repository:
git clone https://github.com/your-username/mcp-think-tool.git
cd mcp-think-tool
Install the dependencies:
npm install
Build the TypeScript code:
npm run build
Start the MCP server:
npm start
To add the Think Tool to Claude Desktop:
{
"mcpServers": {
"think-tool": {
"command": "node",
"args": ["/path/to/mcp-think-tool/build/index.js"]
}
}
}
/path/to/mcp-think-tool with the actual path to your installation.Add this instructional prompt to teach Claude how to use the think tool effectively:
## Using the think tool
Before taking any action or responding to the user after receiving tool results, use the think tool as a scratchpad to:
- List the specific rules that apply to the current request
- Check if all required information is collected
- Verify that the planned action complies with all policies
- Iterate over tool results for correctness
Here are some examples of what to iterate over inside the think tool:
<think_tool_example_1>
User wants to cancel flight ABC123
- Need to verify: user ID, reservation ID, reason
- Check cancellation rules:
* Is it within 24h of booking?
* If not, check ticket class and insurance
- Verify no segments flown or are in the past
- Plan: collect missing info, verify rules, get confirmation
</think_tool_example_1>
<think_tool_example_2>
User wants to book 3 tickets to NYC with 2 checked bags each
- Need user ID to check:
* Membership tier for baggage allowance
* Which payments methods exist in profile
- Baggage calculation:
* Economy class × 3 passengers
* If regular member: 1 free bag each → 3 extra bags = $150
* If silver member: 2 free bags each → 0 extra bags = $0
* If gold member: 3 free bags each → 0 extra bags = $0
- Payment rules to verify:
* Max 1 travel certificate, 1 credit card, 3 gift cards
* All payment methods must be in profile
* Travel certificate remainder goes to waste
- Plan:
1. Get user ID
2. Verify membership level for bag fees
3. Check which payment methods in profile and if their combination is allowed
4. Calculate total: ticket price + any bag fees
5. Get explicit confirmation for booking
</think_tool_example_2>
When solving mathematical problems, Claude can use the think tool to show its work:
Solving 235 × 47:
Think: First I'll break this down. I need to multiply 235 by 47.
Think: I'll start by calculating 235 × 40 = 9,400
Think: Then I'll calculate 235 × 7 = 1,645
Think: Now I add them together: 9,400 + 1,645 = 11,045
Therefore, 235 × 47 = 11,045
For more complex reasoning:
Think: I need to analyze the given problem carefully. The question asks about the impact of reducing carbon emissions by 15% over 5 years.
Think: First, I should establish the baseline emissions. The document mentions current annual emissions of 50 million metric tons.
Think: 15% reduction over 5 years means approximately 3% reduction per year, assuming linear decrease.
Think: After 5 years, annual emissions would be 50 × (1 - 0.15) = 50 × 0.85 = 42.5 million metric tons.
Think: The total reduction over 5 years would be the sum of the reductions each year...
The MCP server exposes a single tool called think with the following definition:
{
"name": "think",
"description": "Use the tool to think about something. It will not obtain new information or change the database, but just append the thought to the log. Use it when complex reasoning or some cache memory is needed.",
"input_schema": {
"type": "object",
"properties": {
"thought": {
"type": "string",
"description": "A thought to think about."
}
},
"required": ["thought"]
}
}
This tool essentially echoes back the input, allowing Claude to organize its thoughts during complex problem-solving tasks.
There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.
If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.
To add a global MCP server go to Cursor Settings > MCP and click "Add new global MCP server".
When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:
{
"mcpServers": {
"cursor-rules-mcp": {
"command": "npx",
"args": [
"-y",
"cursor-rules-mcp"
]
}
}
}
To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.
Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.
The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.
You can also explictly ask the agent to use the tool by mentioning the tool name and describing what the function does.