🔢 Arithmetic + Logic MCP Server

A compact STDIO-based MCP server built in Scala 3 + ZIO + Circe, exposing arithmetic and logic tools through a clean modular architecture.

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🗂️ Project Structure

• Main.scala – boots the server + assembles ZIO layers.
• transport/ – STDIO JSON-RPC engine.
• router/ – message decoding + handler dispatch.
• session/ – session capabilities + initialization lifecycle.
• tools/ – tool definitions, schemas, calculators.
• model/ – JSON-RPC + MCP data models.
• config/ – server config layer.
• util/ – logging helpers.
• test/ – ZIO test suites.

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⚙️ Core Components

1. Transport – reads/writes JSON-RPC through STDIO.
2. Router – matches method names → calls the right handler.
3. Tool Registry – exposes available tools + schemas to MCP.
4. Tool Executor – validated args → computed result.
5. Config Layer – supplies runtime configuration via ZIO.

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🏗️ Startup Logic

ZIO layers stack up as: config → tools → session → router → transport → Main.

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🔄 Request Flow

VS Code → JSON-RPC → STDIO → Router → Tool → STDIO → VS Code.

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🐳 Run with Docker

docker run -it --rm docker.io/roussalex/almcp:latest

Zero Scala/JVM setup required.

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🧪 VS Code Setup

1. CTRL+SHIFT+P → MCP: Add Server
2. Pick Docker image
3. Use roussalex/almcp:latest
4. Optionally set MCP_DEBUG=1

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🤖 Agent Mode Required

Only Copilot Agent Mode extracts arguments + invokes tools. Chat mode cannot call MCP tools.

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🧰 Usage Examples (Agent Mode)

• “List the tools” → returns all arithmetic/logic operators.
• “Add 2 and 3” → MCP infers {a:2, b:3} and executes.
• Same for subtract/multiply/divide/bitwise/comparisons.

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🧷 Testing

ZIO test suites cover:

• initialization
• tool discovery
• routing
• JSON-RPC codecs
• session behavior

CI runs them automatically.

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🔧 Configuration

• Defaults are embedded in ServerConfig.
• Can override with ZIO layer overrides, no special setup needed.

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⚠️ Notes & Limits

• Agent Mode is mandatory.