Encom

Work in progress Ruby implementation of the Model Context Protocol (MCP).

Encom is a Ruby library for implementing both MCP servers and clients. The gem provides a flexible and easy-to-use framework to build applications that can communicate using the MCP specification.

Add this line to your application's Gemfile:

gem 'encom'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install encom

require 'encom/server'
require 'encom/server_transport/stdio'

class MyServer < Encom::Server
  name "MyMCPServer"
  version "1.0.0"
  
  # Define a tool that the server exposes
  tool :hello_world,
       "Says hello to the specified name",
       {
         type: "object",
         properties: {
           name: {
             type: "string",
             description: "The name to greet"
           }
         },
         required: ["name"]
       } do |args|
         { greeting: "Hello, #{args[:name]}!" }
       end
end

# Start the server with a chosen transport mechanism
server = MyServer.new
server.run(Encom::ServerTransport::Stdio)

# Run the server file
ruby my_server.rb

require 'encom/client'
require 'encom/transport/stdio'

# Create a client
client = Encom::Client.new(
  name: 'MyClient',
  version: '1.0.0',
  capabilities: {
    tools: {
      execute: true
    }
  }
)

# Set up error handling
client.on_error do |error|
  puts "ERROR: #{error.class} - #{error.message}"
end

# Connect to an MCP server
transport = Encom::Transport::Stdio.new(
  command: 'ruby',
  args: ['path/to/your/server.rb']
)

client.connect(transport)

# List available tools
tools = client.list_tools

# Call a tool
result = client.call_tool(
  name: 'hello_world',
  arguments: { name: 'World' }
)

puts result[:greeting] # Outputs: Hello, World!

# Close the connection when done
client.close

See the examples directory for complete demonstrations:

• filesystem_demo.rb: Shows how to connect to an MCP filesystem server

• Tools ✅
• Prompts 🟠
• Resources 🟠

We haven't yet added a DSL for defining prompts or resources but these can be defined as shown in bin/mock_mcp_server

• Server tool interface ✅
• Server prompt interface ❌
• Server resource interface ❌
• Roots ❌
• Sampling ❌

Encom currently supports different transport mechanisms for communication:

• STDIO: Communication through standard input/output
• Custom transports can be implemented by extending the base transport classes

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/kylebyrne/encom.

The gem is available as open source under the terms of the MIT License.