pharo-smalltalk-interop-mcp-server

pharo-smalltalk-interop-mcp-server

A local MCP server to communicate local Pharo Smalltalk image.It supports:

• Code Evaluation: Execute Smalltalk expressions and return results
• Code Introspection: Retrieve source code, comments, and metadata for classes and methods
• Search & Discovery: Find classes, traits, methods, references, and implementors
• Package Management: Export and import packages in Tonel format
• Project Installation: Install projects using Metacello
• Test Execution: Run test suites at package or class level

Prerequisites

• Python 3.10 or later
• uv package manager
• Pharo with PharoSmalltalkInteropServer installed

Installation

1. Clone the repository:

git clone <repository-url>
cd pharo-smalltalk-interop-mcp-server

2. Install dependencies using uv:

uv sync --dev

Usage

Running the MCP Server

Start the server:

uv run pharo-smalltalk-interop-mcp-server

Environment Variables

You can configure the server using environment variables:

• PHARO_SIS_PORT: Port number for PharoSmalltalkInteropServer (default: 8086)

Examples:

# Connect to PharoSmalltalkInteropServer on port 8081
PHARO_SIS_PORT=8081 uv run pharo-smalltalk-interop-mcp-server

# Connect to PharoSmalltalkInteropServer on port 9999
PHARO_SIS_PORT=9999 uv run pharo-smalltalk-interop-mcp-server

Cursor MCP settings

{
  "mcpServers": {
    "pharo-smalltalk-interop-mcp-server": {
      "command": "uv",
      "args": [
        "--directory",
        "/your-path/to/pharo-smalltalk-interop-mcp-server",
        "run",
        "pharo-smalltalk-interop-mcp-server"
      ],
      "env": {
        "PHARO_SIS_PORT": "8081"
      }
    }
  }
}

Note: The env section is optional and can be used to set environment variables for the MCP server.

Claude Code Configuration

Add to your Claude Code settings:

claude mcp add smalltalk-interop -- uv --directory /path/to/pharo-smalltalk-interop-mcp-server run pharo-smalltalk-interop-mcp-server

MCP Tools Available

This server provides 19 MCP tools that map to all PharoSmalltalkInteropServer APIs:

Code Evaluation

• eval: Execute Smalltalk expressions and return results

Code Introspection

• get_class_source: Retrieve source code of a class
• get_method_source: Retrieve source code of a specific method
• get_class_comment: Retrieve comment/documentation of a class

Search & Discovery

• search_classes_like: Find classes matching a pattern
• search_methods_like: Find methods matching a pattern
• search_traits_like: Find traits matching a pattern
• search_implementors: Find all implementors of a method selector
• search_references: Find all references to a method selector
• search_references_to_class: Find all references to a class

Package Management

• list_packages: List all packages in the image
• list_classes: List classes in a specific package
• list_extended_classes: List extended classes in a package
• list_methods: List methods in a package
• export_package: Export a package in Tonel format
• import_package: Import a package from specified path

Project Installation

• install_project: Install a project using Metacello with optional load groups

Test Execution

• run_package_test: Run test suites for a package
• run_class_test: Run test suites for a specific class

Development

Running Tests

The project includes comprehensive unit tests with mock-based testing to avoid requiring a live Pharo instance:

# Run all tests
uv run pytest

# Run tests with verbose output
uv run pytest -v

# Run specific test file
uv run pytest tests/test_core.py -v

Code Quality

# Run linting
uv run ruff check

# Run formatting
uv run ruff format

# Run all pre-commit hooks
uv run pre-commit run --all-files

Project Structure

pharo-smalltalk-interop-mcp-server/
├── pharo_smalltalk_interop_mcp_server/
│   ├── __init__.py
│   ├── core.py          # HTTP client and core functions
│   └── server.py        # FastMCP server with tool definitions
├── tests/
│   ├── __init__.py
│   ├── test_core.py     # Tests for core HTTP client functionality
│   └── test_server.py   # Tests for MCP server integration
├── pyproject.toml       # Project configuration
├── pytest.ini          # Test configuration
└── README.md

Testing Strategy

The test suite uses mock-based testing to ensure:

• No external dependencies: Tests run without requiring a live Pharo instance
• Comprehensive coverage: All 19 endpoints and error scenarios are tested
• Fast execution: Tests complete in under 1 second
• Reliable results: Tests are deterministic and don't depend on external state

Test coverage includes:

• HTTP client functionality (PharoClient class)
• All 19 Pharo interop operations
• Error handling (connection errors, HTTP errors, JSON parsing errors)
• MCP server initialization and tool registration
• Integration between core functions and MCP tools