vancouver

[](https://github.com/jameslong/vancouver/actions/workflows/test.yml) [](https://hex.pm/packages/vancouver) [](https://hexdocs.pm/vancouver/) [](https://hex.pm/packages/vancouver) [](https://hex.pm/packages/vancouver) # Vancouver Vancouver makes it easy to add [Model Context Protocol (MCP)](https://modelcontextprotocol.io/introduction) functionality to your Phoenix/Bandit server. Vancouver handles initialization, request validation, and offers helper functions to simplify the creation of MCP tools and prompts. ## Getting started ### 1. Add dependency In `mix.exs`: ```elixir defp deps do [ {:vancouver, "~> 0.3"} ] end ``` ### 2. Create your tools/prompts You can implement tools like this: ```elixir defmodule MyApp.Tools.CalculateSum do use Vancouver.Tool def name, do: "calculate_sum" def description, do: "Add two numbers together" def input_schema do %{ "type" => "object", "properties" => %{ "a" => %{"type" => "number"}, "b" => %{"type" => "number"} }, "required" => ["a", "b"] } end def run(conn, %{"a" => a, "b" => b}) do send_text(conn, "#{a + b}") end end ``` And prompts like this: ```elixir defmodule MyApp.Prompts.CodeReview do use Vancouver.Prompt def name, do: "code_review" def description, do: "Asks the LLM to analyze code quality and suggest improvements" def arguments do [ %{ "name" => "code", "description" => "The code to review", "required" => true } ] end def run(conn, %{"code" => code}) do send_text(conn, "Please review this code: #{code}") end end ``` ### 3. Add config In `config.ex`: ```elixir config :vancouver, name: "My MCP Server", version: "1.0.0" ``` ### 4. Add your MCP route In `router.ex`: ```elixir forward "/mcp", Vancouver.Router, tools: [MyApp.Tools.CalculateSum], prompts: [MyApp.Prompts.CodeReview] ``` ### 5. (Optional) Add to your MCP client E.g. For Claude Desktop, you can modify your config `Settings -> Developer -> Edit config` as follows: { "mcpServers": { "MyApp": { "command": "npx", "args": [ "mcp-remote", "http://localhost:4000/mcp" ] } } } Run your server, and restart Claude to starting using your MCP tools. 🚀 ## FAQ ### Does Vancouver support all parts of the Model Context Protocol specification? Not yet. Vancouver currently supports: - tools - prompts - sync responses (no streaming) However, the library is simple enough that you should be able to modify it for your needs. For more info on the protocol itself, see the [MCP User Guide](https://modelcontextprotocol.io/introduction). ### Is Vancouver stable / ready for production? No. This library is in early development. Expect breaking changes. ### Why is this library called Vancouver? Vancouver is the natural home of MCP (Mountain, Coffee, and Phoenix).