mcp-tool-chainer

# MCP Tool Chainer [](https://thirdstrandstudio.com) 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)  Step function like JSON paths:  ## 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.  ## 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://thirdstrandstudio.com)