Tidewave Rails MCP
An MCP server exposes a running development Rails app to agents for Ruby, SQL, logs and version-matched gem documentation.
- 475 ★ on the repository
- Last commit
- Apache-2.0
Broad access
Why this level
- The agent executes Ruby and arbitrary SQL with the running application’s access.
Install
- Works in
Manual install
bundle add tidewave --group developmentThe first README command adds the gem to the development group.
Access and checks
How we reviewBroad accessThe tool can change data, run commands or handle secrets.
- The agent executes Ruby and arbitrary SQL with the running application’s access.
This is third-party code. Review the repository files before installing.
What it does
Tidewave Rails runs inside an application’s development environment. Agents can execute Ruby, query the development database, inspect logs and locate method definitions, including dynamically generated ones. Documentation comes from gem versions locked in Gemfile.lock, helping verify actual behavior before an edit. Clients connect over HTTP, and the server works independently of the full Tidewave product. Access is restricted to localhost by default.
Who it is for. For Rails developers exposing a test application’s actual runtime state alongside source.
Good fit when
- Reproduce a bug in current application state.
- Locate a dynamically generated method.
- Inspect a development record after an action.
- Use documentation matching installed gem versions.
Not a fit when
- The target is a production application.
- Ruby and SQL execution in the application is prohibited.
- Development data cannot be exposed to the model.
Example request
In the test Rails app, locate this method and show its gem documentation before any SQL execution.MCP
- Transport
- http
- Authentication
- not required
Limitations
The server targets development rather than production and errors in environments without code reloading. Ruby and SQL run with application access, so use a separate test database and limited credentials. Requests are restricted to localhost by default; enable remote access only in a protected environment. Middleware adjusts CSP for contextual browser testing, so inspect development settings and do not carry them into production.
How to disable. Remove Tidewave from development dependencies, restart Rails and remove the client’s MCP endpoint. Inspect changed test data separately.
FAQ
Which tool executes Ruby?
`project_eval` inside the running application.
How is SQL executed?
Through `execute_sql_query` against the development database.
Where do documentation versions come from?
From the application’s `Gemfile.lock` dependencies.
Is the full Tidewave product required?
No. This MCP component can be used independently.
What is the endpoint for Rails on port 3000?
`http://localhost:3000/tidewave/mcp`.
Discussion
No questions or reviews yet.
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