webmcp-rails

Rails helpers for WebMCP, a W3C standard that lets websites expose HTML forms as structured tools for AI agents.

Adds a webmcp: option to form_with, form_for, and all form input helpers.

Installation

gem "webmcp-rails"

Usage

form_with model: @todo, webmcp: { tool: "addTodo", description: "Add a new todo item", autosubmit: true } do |f|
  f.text_field :title, webmcp: { param_description: "Title of the todo" }
  f.date_field :due_date, webmcp: { param_description: "Due date", param_title: "Due Date" }
  f.submit "Add"
end

Renders:

<form toolname="addTodo" tooldescription="Add a new todo item" toolautosubmit action="/todos" method="post">
  <input type="text" name="todo[title]" toolparamdescription="Title of the todo" />
  <input type="date" name="todo[due_date]" toolparamdescription="Due date" toolparamtitle="Due Date" />
  <input type="submit" value="Add" />
</form>

Form options

Ruby key	HTML attribute	Description
tool:	toolname	Tool name exposed to AI agents
description:	tooldescription	Human-readable tool description
autosubmit:	toolautosubmit	Allow agents to submit without confirmation

Field options

Ruby key	HTML attribute	Description
param_description:	toolparamdescription	Parameter description
param_title:	toolparamtitle	Display title for the parameter

Supported field helpers

text_field, email_field, password_field, number_field, date_field, datetime_field, time_field, url_field, telephone_field, search_field, text_area, color_field, range_field, hidden_field, select

Requirements

• Ruby >= 3.1
• Rails >= 7.0

License

MIT