Tidewave MCP Dev Tools

Tidewave is a dev tool by Dashbit that connects AI coding assistants to running Phoenix applications via the Model Context Protocol (MCP). It exposes runtime introspection tools: Ecto schemas, code execution, documentation lookup, log inspection, and SQL queries.

Current version: ~> 0.5 (v0.5.6 released 2026-03-13)

Installation

New Projects (via Igniter)

mix archive.install hex igniter_new
mix igniter.install tidewave

Existing Projects (Manual)

1. Add to mix.exs:

defp deps do
  [
    {:tidewave, "~> 0.5", only: :dev}
  ]
end

2. Add plug to lib/my_app_web/endpoint.ex before the code_reloading? block:

if Mix.env() == :dev do
  plug Tidewave
end

if code_reloading? do
  # ...existing code reload plugs...
end

3. Fetch dependencies:

mix deps.get

Umbrella Projects

Apply the manual steps to the application defining the Phoenix endpoint (typically apps/your_app_web).

MCP Server Configuration

Tidewave exposes an MCP server at /tidewave/mcp on the Phoenix app's port. The transport type is HTTP (streamable).

Default URL: http://localhost:4000/tidewave/mcp

Claude Code

claude mcp add --transport http tidewave http://localhost:4000/tidewave/mcp

Add to CLAUDE.md to encourage MCP tool usage:

Always use Tidewave's tools for evaluating code, querying the database, etc.
Use `get_docs` to access documentation and `get_source_location` to find module/function definitions.

Other Editors

Editor	Config File	URL Key
Cursor	.cursor/mcp.json	mcpServers.tidewave.url
VS Code	.vscode/mcp.json	servers.tidewave.url
Zed	Zed settings.json	context_servers.tidewave.settings.url

All use URL: http://localhost:4000/tidewave/mcp

MCP Tools Reference

Tool	Description
project_eval	Execute Elixir code within the running application runtime
execute_sql_query	Run SQL queries against the application database
get_ecto_schemas	List all Ecto schema modules with their fields and associations
get_ash_resources	List all Ash resources (when using the Ash framework)
get_docs	Retrieve documentation for modules/functions using exact project versions
search_package_docs	Query hexdocs.pm filtered to project dependencies (availability varies by framework)
get_source_location	Find module/function source code file paths and line numbers
get_models	List all application modules with their file locations
get_logs	Access server logs; supports log level filtering (added v0.5.5)

Note: search_package_docs may not be available in all frameworks. Verify availability for your setup.

Usage Patterns

Introspect schemas before writing queries:

get_ecto_schemas → discover schema structure → execute_sql_query

Look up documentation for project dependencies:

get_docs for specific modules, search_package_docs for broader hex dependency searches

Execute and test code in the running app:

project_eval → run Elixir expressions against live application state

Plug Configuration Options

if Mix.env() == :dev do
  plug Tidewave,
    allow_remote_access: false,
    inspect_opts: [pretty: true, limit: 50]
end

Option	Default	Description
allow_remote_access	false	Allow connections from non-localhost
inspect_opts	[]	Options passed to Kernel.inspect/2 for output formatting
team	nil	Team configuration (e.g., [id: "my-company"])

CLI App (Standalone MCP Server)

The Tidewave desktop/CLI app (tidewave_app) runs a standalone MCP server without requiring a Phoenix application. Useful for containers, remote dev environments, or non-Phoenix Elixir projects.

• Default server: http://localhost:9832
• Only allows access from the same machine by default

Installation

• Desktop app (macOS, Windows, Linux): https://tidewave.ai/install
• Development CLI: cargo run -p tidewave-cli [-- --help]

When to Use CLI vs Phoenix Plug

Scenario	Use
Phoenix application	plug Tidewave in endpoint.ex
Container/remote dev	CLI app or plug with allow_remote_access: true
Non-Phoenix Elixir	CLI app
Standalone MCP server	CLI app on port 9832

LiveView Debug Annotations

Enable in config/dev.exs to help Tidewave map rendered HTML back to source HEEx templates:

config :phoenix_live_view,
  debug_heex_annotations: true

config :phoenix,
  debug_attributes: true

Requires Phoenix LiveView v1.1+ (current: 1.1.27).

Security

• Dev-only: Always guard with Mix.env() == :dev or only: :dev in deps
• Localhost-only: Tidewave only accepts localhost requests by default
• No production use: Tidewave exposes code execution and database access — never deploy to production
• Docker/remote dev: Set allow_remote_access: true only on trusted networks
• CSP: Tidewave injects unsafe-eval in script-src directives and disables frame-ancestors restrictions

Troubleshooting

MCP connection fails

• Verify Phoenix server is running: mix phx.server
• Check the port matches your configuration (default 4000)
• Try http://127.0.0.1:4000/tidewave/mcp if IPv6 causes issues

Tools not appearing

• Confirm plug Tidewave is placed before if code_reloading? in endpoint.ex
• Restart the Phoenix server after adding the plug
• Verify the dependency is installed: mix deps.get

Claude Code authentication error

• Run claude in your terminal and confirm authentication
• Verify CLI availability: which claude

Umbrella project issues

• Add the plug only in the endpoint of the web application
• Ensure :tidewave is added to the correct mix.exs in the umbrella