pharo-mcp-server

# Pharo MCP Server [](https://opensource.org/licenses/MIT) [](https://mcpreview.com/mcp-servers/paulwilke/pharo-mcp-server) <!-- Add other badges later, e.g., build status, version --> **Pharo Smalltalk implementation of Anthropic's Model Context Protocol (MCP) server specification. Enables LLMs like Claude to interact with Pharo applications.** --- ## Table of Contents * [What is MCP?](#what-is-mcp) * [Goal of this Project](#goal-of-this-project) * [Features](#features) * [Installation](#installation) * [Basic Usage](#basic-usage) * [Defining Tools](#defining-tools) * [Configuration](#configuration) * [Development & Contributing](#development--contributing) * [License](#license) ## What is MCP? The Model Context Protocol (MCP), developed by Anthropic, is a specification designed to standardize how Large Language Models (LLMs) interact with external tools and services. It defines mechanisms for: 1. **Discovery:** How an LLM finds out if a service supports MCP and gets basic information. 2. **Service Description:** How a service describes its available tools (functions), including their names, purposes, input parameters, and output formats. 3. **Invocation:** How an LLM securely calls a specific tool with the required arguments and receives the result. The goal is to make LLM tool usage more reliable, secure, and standardized. For more details, see the official [Model Context Protocol GitHub organization](https://github.com/modelcontextprotocol). ## Goal of this Project This project aims to provide a robust and easy-to-use **server-side implementation of the MCP specification** specifically for the **Pharo Smalltalk** environment. It allows developers to expose functionalities within their Pharo applications (like querying data, creating objects, triggering actions) as "tools" that MCP-compliant LLMs (such as Claude 3) can discover and invoke through the standardized protocol. This bridges the gap between the dynamic Pharo environment and the capabilities of modern LLMs. ## Features * **MCP Specification Compliance:** Implements the core server-side endpoints: * Discovery (`/.well-known/model-context`) * Service Description (`/mcp/description` - or configurable path) * Invocation (`/mcp/invoke` - or configurable path) * **Dynamic Tool Registration:** Provides a simple API to register Pharo methods or blocks as MCP tools. * **Automatic Service Description:** Generates the MCP Service Description JSON based on the registered tools and their metadata (name, description, schemas). * **Web Server Integration:** Built upon the [Teapot](https://github.com/pharo-web/teapot) micro web framework. * **JSON Handling:** Uses [NeoJSON](https://github.com/svenvc/NeoJSON) for robust JSON parsing and generation. * **Extensible:** Designed to be integrated into larger Pharo applications. * **(Planned):** Input validation using JSON Schema definitions for tool parameters. * **(Planned):** Integration helpers for common Pharo object models (e.g., using [Voyage](https://github.com/pharo-nosql/voyage)). ## Installation This project is intended to be loaded using Metacello. 1. **Ensure Metacello is loaded** in your Pharo image (it usually is). 2. **Execute the following code** in a Pharo Workspace (adjust the repository URL and branch/tag if necessary): ```smalltalk Metacello new baseline: 'MCPFramework'; "<- Use the actual name of YOUR baseline class (without 'BaselineOf')" repository: 'github://YOUR_USERNAME/pharo-mcp-server:main/'; "<- CHANGE THIS to your repo URL and branch/tag" load.