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.
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
- MIT License