Integrations
Used for cloning the repository during installation process.
Referenced for issue tracking and contributions to the MCP server project.
Supported as a deployment platform for running the MCP server.
MCP Expr-Lang
A powerful expression evaluation tool for Claude Desktop using the Model Context Protocol (MCP).
Overview
MCP Expr-Lang provides a seamless integration between Claude AI and the powerful expr-lang expression evaluation engine. This tool allows you to perform complex data manipulations, calculations, and transformations directly within your Claude conversations.
With MCP Expr-Lang, you can:
- Evaluate mathematical expressions
- Transform and filter arrays and objects
- Sort complex data structures
- Perform string manipulations
- Use conditional logic
- And much more!
Installation
Installing via Smithery
To install MCP Expr-Lang for Claude Desktop automatically via Smithery:
Prerequisites
- Go 1.18 or higher
- Claude Desktop application
- Git
Step 1: Clone the Repository
Step 2: Install Dependencies
Step 3: Build the Application
For Windows
For macOS/Linux
Step 4: Configure Claude Desktop
- Open Claude Desktop
- Go to Settings
- Navigate to the "Advanced" section
- Add the following configuration to your
config.json
:
For Windows
For macOS/Linux
- Save the configuration and restart Claude Desktop
Usage
Once installed, you can use the eval
tool directly in your conversations with Claude. Simply ask Claude to evaluate an expression using the tool.
Basic Example
Complex Example
For more examples please see EXAMPLES
Features
MCP Expr-Lang supports all features of the expr-lang engine, including:
- Arithmetic operations: Addition, subtraction, multiplication, division, modulo, exponentiation
- String operations: Concatenation, length, uppercase/lowercase conversion
- Boolean operations: AND, OR, NOT, comparison operators
- Array operations: Mapping, filtering, reducing, sorting
- Object manipulation: Property access, transformation
- Conditional logic: Ternary operators, if-else expressions
- Built-in functions: Mathematical, string, array, and date functions
For a complete guide to the expression language syntax and capabilities, see the expr-lang documentation.
Troubleshooting
Common Issues
- Tool not appearing in Claude: Make sure the path in your
config.json
is correct and Claude Desktop has been restarted. - Execution errors: Check that the expression syntax is correct according to the expr-lang documentation.
- Permission issues (macOS/Linux): Ensure the server binary has execution permissions (
chmod +x bin/server
).
Getting Help
If you encounter any issues or have questions:
- Check the Issues section on GitHub
- Open a new issue if your problem hasn't been reported
Contributing
Contributions are welcome! If you'd like to improve MCP Expr-Lang:
- Fork the repository
- Create a feature branch (
git checkout -b feature/amazing-feature
) - Commit your changes (
git commit -m 'Add some amazing feature'
) - Push to the branch (
git push origin feature/amazing-feature
) - Open a Pull Request
License
This project is licensed under the MIT License - see the LICENSE file for details.
Acknowledgments
- expr-lang for the powerful expression evaluation engine
- mcp-golang for the Model Context Protocol implementation
- Claude AI for the AI assistant platform
Made with ❤️ by Ivan Saorin
This server cannot be installed
local-only server
The server can only run on the client's local machine because it depends on local resources.
MCP Expr Lang
Related MCP Servers
- JavaScriptMIT License
- Gozlib License
- PythonApache 2.0
- TypeScriptMIT License