[md]Scala MCP Library

A Scala 3 library for building Model Context Protocol (MCP) servers. MCP is a JSON-RPC 2.0 based protocol that allows AI applications like Claude to access tools, resources, and prompts.

Highlights

• Type-safe protocol implementation with Scala 3 enums and opaque types
• Automatic JSON Schema derivation via derives JsonSchema
• Multiple transport layers — stdio for subprocess servers, Streamable HTTP + SSE for networked servers
• Cross-platform — core, stdio, and http4s all run on JVM, Scala.js, and Scala Native
• Fluent builder API for servers, tools, resources, and prompts
• Effect-polymorphic, built on Cats Effect
• Zero-boilerplate codec derivation with Scala 3's derives syntax

Where to next

• Introduction → MCP feature support — what's implemented vs. what isn't
• Getting Started → Quick start — add the dependency and write your first tool
• Getting Started → Tools, Resources, Prompts — the core building blocks
• Getting Started → JSON schema derivation — derives JsonSchema and annotations
• Getting Started → Server construction — Stdio + HTTP transports
• Clients — McpClient over stdio or HTTP, plus handlers for server-initiated sampling / elicitation / roots requests
• Modules — one page per module (core, stdio, http4s, openapi, redis, tapir, golden-munit, explorer)
• Tools → OpenAPI MCP Proxy — turn any OpenAPI API into an MCP server
• Testing → Golden testing — snapshot-test your server's spec
• Examples — six runnable example servers covering every transport
• Using an LLM? Point it at llms.txt for a structured index of every doc page, or llms-full.txt for the entire documentation in a single file. Each page is also available as raw Markdown — swap .html for .md in any URL. Tell your assistant to start at llms.txt and follow the links rather than scraping the HTML.