---
slug: "mcp-tool-chainer"
source_type: "readme"
source_url: "https://cdn.jsdelivr.net/gh/thirdstrandstudio/mcp-tool-chainer@main/README.md"
repo: "https://github.com/thirdstrandstudio/mcp-tool-chainer"
source_file: "README.md"
branch: "main"
---
# MCP Tool Chainer

[![Visit Third Strand Studio](https://img.shields.io/badge/Visit-Third%20Strand%20Studio-blue)](https://tss.topiray.com/products/mcp-chain)

An MCP (Model Context Protocol) server that chains calls to other MCP tools, reducing token usage by allowing sequential tool execution with result passing.
Designed to solve [https://github.com/modelcontextprotocol/specification/issues/215](https://github.com/modelcontextprotocol/specification/issues/215)

![image](https://github.com/user-attachments/assets/3c0336a3-dd24-4dd9-88db-ac4704ee437e)


Step function like JSON paths:

![image](https://github.com/user-attachments/assets/79ef5c3e-6166-4bc4-b571-e7b3176e777c)


## Features

- Chain multiple MCP tools together in sequence
- Pass results from one tool as input to another tool using `CHAIN_RESULT` placeholder
- Filter and extract specific data using JsonPath with `inputPath` and `outputPath` parameters
- Automatic tool discovery from configured MCP servers
- Minimal token usage compared to individual tool calls

## Tools

This server implements the following MCP tools:

1. `mcp_chain` - Chain together multiple MCP servers
2. `chainable_tools` - Discover tools from all MCP servers so the mcp_chain tool can be used
3. `discover_tools` - Rediscover tools from all MCP servers

## Installation

### Prerequisites

* Node.js (v16 or later)
* npm

### Installing from npm

```bash
# Install
npm install @thirdstrandstudio/mcp-tool-chainer

# Or use with npx directly
npx -y @thirdstrandstudio/mcp-tool-chainer
```

### Installing from source

```bash
# Clone the repository
git clone https://github.com/thirdstrandstudio/mcp-tool-chainer.git
cd mcp-tool-chainer

# Install dependencies
npm install

# Build the package
npm run build
```

## Usage with Claude Desktop, Cursor etc

ENSURE IT IS THE LAST MCP TO RUN OTHERWISE IT WILL HAVE TO RUN DISCOVERY AGAIN

Add the following to your `claude_desktop_config.json` or `mcp.json`:

### If installed from npm globally

```json
{
  "mcpServers": {
    "mcp_tool_chainer": {
      "command": "npx",
      "args": ["-y", "@thirdstrandstudio/mcp-tool-chainer", "`claude_desktop_config.json` or `mcp.json`"],
      "env": {}
    }
  }
}
```

### If installed from source

```json
{
  "mcpServers": {
    "mcp_tool_chainer": {
      "command": "node",
      "args": ["/path/to/mcp-tool-chainer/dist/index.js", "`claude_desktop_config.json` or `mcp.json`"],
      "env": {}
    }
  }
}
```

Replace `/path/to/mcp-tool-chainer` with the actual path to your repository.

![image](https://github.com/user-attachments/assets/667468c4-aeba-4ea1-b65a-fd7a5922a23b)


## Examples

### Chain Browser and XPath Tools

```javascript
// Fetch a webpage and then extract specific content with XPath
const result = await callTool("mcp_chain", { 
  "mcpPath": [
    {
      "toolName": "mcp_browser_mcp_fetch_url",
      "toolArgs": "{\"url\": \"https://example.com\"}"
    },
    {
      "toolName": "mcp_xpath_xpath",
      "toolArgs": "{\"xml\": CHAIN_RESULT, \"query\": \"//h1\"}"
    }
  ]
});
```

### Using JsonPath with InputPath and OutputPath

```javascript
// Fetch a webpage, extract specific content with XPath, then extract part of the result
const result = await callTool("mcp_chain", { 
  "mcpPath": [
    {
      "toolName": "mcp_fetch_fetch",
      "toolArgs": "{\"url\": \"https://api.example.com/data\"}"
    },
    {
      "toolName": "web_search",
      "toolArgs": "{\"search_term\": CHAIN_RESULT}",
      "inputPath": "$.results[0].title",     // Extract only the first result's title from previous output
      "outputPath": "$.snippets[*].text"     // Extract only the text snippets from the search results
    },
    {
      "toolName": "another_tool",
      "toolArgs": "{\"content\": CHAIN_RESULT}"
    }
  ]
});
```

## JsonPath Support

MCP Tool Chainer now supports AWS Step Functions-style InputPath and OutputPath features:

- **inputPath**: JsonPath expression to extract specific portions of the input before passing to a tool
- **outputPath**: JsonPath expression to extract specific portions of the output before passing to the next tool

These features work only when the input/output is valid JSON. If JsonPath extraction fails, the original input/output is used.

For JsonPath syntax reference, see [JsonPath Syntax](https://goessner.net/articles/JsonPath/).

## Benefits

- **Reduced Token Usage**: By chaining tools together, you avoid sending large intermediate results back to the LLM
- **Simplified Workflows**: Create complex data processing pipelines with a single tool call
- **Improved Performance**: Reduce latency by minimizing round-trips between the LLM and tools
- **Precise Data Flow Control**: Extract only the data you need with JsonPath expressions

## Development

```bash
# Install dependencies
npm install

# Start the server
node dist/index.js config.json

# List available tools
node dist/index.js config.json discover_tools
```

## License

This MCP server is licensed under the MIT License.

---

Created by [Third Strand Studio](https://tss.topiray.com/products/mcp-chain)