A high-performance Model Context Protocol (MCP) implementation in Elixir.
Hermes MCP is a comprehensive Elixir SDK for the Model Context Protocol, providing complete client and server implementations with Elixir's exceptional concurrency model and fault tolerance.
def deps do
[
{:hermes_mcp, "~> 0.10.5"} # x-release-please-version
]
end# Define a server with tools capabilities
defmodule MyApp.MCPServer do
use Hermes.Server,
name: "My Server",
version: "1.0.0",
capabilities: [:tools]
def start_link(opts) do
Hermes.Server.start_link(__MODULE__, :ok, opts)
end
component MyApp.MCPServer.EchoTool
@impl true
def init(:ok, frame), do: {:ok, frame}
end
# Define your tool
defmodule MyApp.MCPServer.EchoTool do
@moduledoc "This tool echoes everything the user says to the LLM"
use Hermes.Server.Component, type: :tool
alias Hermes.Server.Response
schema do
field :text, {:string, {:max, 500}},
description: "The text to be echoed, max of 500 chars",
required: true
end
@impl true
def execute(%{text: text}, frame) do
{:reply, Response.text(Response.tool(), text), frame}
end
end
# Add to your application supervisor
children = [
Hermes.Server.Registry,
{MyApp.MCPServer, transport: :streamable_http}
]
# Add to your Plug/Phoenix router (if using HTTP)
forward "/mcp", Hermes.Server.Transport.StreamableHTTP.Plug, server: MyApp.MCPServer# Define a client module
defmodule MyApp.AnthropicClient do
use Hermes.Client,
name: "MyApp",
version: "1.0.0",
protocol_version: "2024-11-05",
capabilities: [:roots, :sampling]
end
# Add to your application supervisor
children = [
{MyApp.AnthropicClient,
transport: {:stdio, command: "uvx", args: ["mcp-server-anthropic"]}}
]
# Use the client
{:ok, tools} = MyApp.AnthropicClient.list_tools()
{:ok, result} = MyApp.AnthropicClient.call_tool("search", %{query: "elixir"})Named after Hermes, the Greek god of boundaries and communication, this library facilitates seamless interaction between Large Language Models and external tools - serving as a messenger between AI and data sources.
For detailed guides and examples, visit the official documentation.
MIT License. See LICENSE for details.