# The Official Ruby SDK for MCP Reaches 1.0

> Source: <https://blog.modelcontextprotocol.io/posts/ruby-sdk-1-0/>
> Published: 2026-07-27 09:00:00+00:00

[Version 1.0.0](https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v1.0.0) of the official [Ruby SDK](https://github.com/modelcontextprotocol/ruby-sdk) for the Model Context Protocol is now available. This is the first stable release of the [ mcp gem](https://rubygems.org/gems/mcp): the public API is now stable, and breaking changes ship only in major releases, following the Semantic Versioning policy documented in

[VERSIONING.md](https://github.com/modelcontextprotocol/ruby-sdk/blob/main/VERSIONING.md).

Alongside the release, the Ruby SDK now meets every Tier 2 requirement of the [SDK tiering system](https://modelcontextprotocol.io/community/sdk-tiers), as recorded in the [Tier 2 assessment](https://github.com/modelcontextprotocol/modelcontextprotocol/issues/3127), and development toward Tier 1 is ongoing.

## What is in 1.0[#](#what-is-in-10)

The 1.0 release implements the 2025-06-18 and 2025-11-25 specification revisions and passes 100% of the server and client conformance scenarios. It includes:

- MCP servers with tools, prompts, resources (including templates and subscriptions), completions, logging, pagination, progress, and cancellation, plus server-to-client requests for sampling, elicitation (form and URL mode), and roots
- An MCP client with a complete OAuth flow, including dynamic client registration, PKCE, and scope handling
- stdio and Streamable HTTP transports; the HTTP transport is a standard Rack app, so it can be mounted directly in Rails routes or any Rack-compatible framework

## From Tier 3 to Tier 2[#](#from-tier-3-to-tier-2)

The Ruby SDK was assessed at [Tier 3](https://github.com/modelcontextprotocol/modelcontextprotocol/issues/2340) in March 2026. Since then:

- Server conformance moved from 83.3% to 100%, with no baselined failures
- A conformance client was implemented and passes 100% of client scenarios
- Sampling, elicitation, and progress notifications were implemented on both the server and client sides
[ROADMAP.md](https://github.com/modelcontextprotocol/ruby-sdk/blob/main/ROADMAP.md)and[VERSIONING.md](https://github.com/modelcontextprotocol/ruby-sdk/blob/main/VERSIONING.md)were published

Work is also under way to support the upcoming [2026-07-28 specification release](/posts/sdk-betas-2026-07-28/).

## Get started[#](#get-started)

Install the gem:

``` bash
$ gem install mcp
```

A minimal stdio server looks like this:

```
require "mcp"

class ExampleTool < MCP::Tool
  description "A simple example tool that echoes back its arguments"
  input_schema(
    properties: {
      message: { type: "string" },
    },
    required: ["message"]
  )

  class << self
    def call(message:, server_context:)
      MCP::Tool::Response.new([{
        type: "text",
        text: "Hello from example tool! Message: #{message}",
      }])
    end
  end
end

server = MCP::Server.new(
  name: "example_server",
  tools: [ExampleTool],
)

MCP::Server::Transports::StdioTransport.new(server).open
```

See the [Ruby SDK documentation](https://ruby.sdk.modelcontextprotocol.io) for guides on building servers and clients, including Rails integration.

## Give us your feedback[#](#give-us-your-feedback)

If you run into problems or unexpected behavior while using the SDK, please report them on the [issue tracker](https://github.com/modelcontextprotocol/ruby-sdk/issues). Reports from real-world usage are especially valuable.

The Ruby SDK began at [Shopify](https://www.shopify.com/) and is maintained by [Topher Bullock](https://github.com/topherbullock), [Koichi Ito](https://github.com/koic), [Ateş Göral](https://github.com/atesgoral), and [Jonathan Hefner](https://github.com/jonathanhefner) together with the wider Ruby community. Thank you to everyone for the feedback and contributions on the road to 1.0.