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 modelcontextprotocol/modelcontextprotocol#215

Step function like JSON paths:

• 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

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

• Node.js (v16 or later)
• npm

# Install npm install @thirdstrandstudio/mcp-tool-chainer # Or use with npx directly npx -y @thirdstrandstudio/mcp-tool-chainer

# 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

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:

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

{ "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.

// 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\"}" } ] });

// 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}" } ] });

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.

• 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

# Install dependencies npm install # Start the server node dist/index.js config.json # List available tools node dist/index.js config.json discover_tools

This MCP server is licensed under the MIT License.

Created by Third Strand Studio