Frequently Asked Questions (FAQ) about MCP Expr-Lang

Q: What is MCP Expr-Lang? A: MCP Expr-Lang is an integration tool that connects Claude AI with the expr-lang expression evaluation engine. It allows you to perform complex data manipulations, calculations, and transformations directly within your Claude conversations.

Q: What is the Model Context Protocol (MCP)? A: MCP is an open protocol that standardizes how applications provide context to LLMs. MCP (Model Context Protocol) server acts as a bridge, allowing AI models to access and interact with external data sources and tools.

Q: What can I do with MCP Expr-Lang? A: You can evaluate mathematical expressions, transform and filter arrays and objects, sort complex data structures, perform string manipulations, use conditional logic, and much more.

Q: How do I install MCP Expr-Lang? A: You can install MCP Expr-Lang automatically via Smithery or manually by cloning the repository, installing dependencies, building the application, and configuring Claude Desktop.

Q: What are the prerequisites for installing MCP Expr-Lang? A: You need Go 1.18 or higher, the Claude Desktop application, and Git.

Q: How do I configure Claude Desktop to use MCP Expr-Lang? A: You need to add a configuration to your config.json file in the Advanced section of Claude Desktop settings, specifying the path to the server executable.

Q: How do I use MCP Expr-Lang in my conversations with Claude? A: Simply ask Claude to evaluate an expression using the eval tool. For example: “Use eval to calculate ‘10 + 5 * 3’”.

Q: What features does MCP Expr-Lang support? A: MCP Expr-Lang supports all features of the expr-lang engine, including arithmetic operations, string operations, boolean operations, array operations, object manipulation, conditional logic, and built-in functions.

Q: Where can I find more information about the expr-lang syntax and capabilities? A: See the expr-lang documentation.

Q: What should I do if the tool is not appearing in Claude? A: Make sure the path in your config.json is correct and Claude Desktop has been restarted.

Q: What should I do if I encounter execution errors? A: Check that the expression syntax is correct according to the expr-lang documentation.

Q: What should I do if I have permission issues on macOS/Linux? A: Ensure the server binary has execution permissions (chmod +x bin/server).

Q: Where can I get help if I encounter issues or have questions? A: Check the Issues section on GitHub or open a new issue if your problem hasn’t been reported.

Q: Can I contribute to MCP Expr-Lang? A: Yes, contributions are welcome! Fork the repository, create a feature branch, commit your changes, push to the branch, and open a Pull Request.

Q: What license is MCP Expr-Lang released under? A: This project is licensed under the MIT License.

Q: How does UBOS enhance the use of MCP Expr-Lang? A: UBOS is a full-stack AI Agent Development Platform that allows you to orchestrate AI Agents, connect them with your enterprise data, build custom AI Agents with your LLM model and Multi-Agent Systems, complementing the capabilities of MCP Expr-Lang within a broader AI ecosystem.