WebMCP Integration Tests Drupal Forms as Browser-Agent Tools

Drupal developer Ronald te Brake has built a WebMCP Integration proof of concept that lets opted-in Drupal forms expose structured capabilities to browser-based AI agents. In a 6 September 2026 post, he described tests with Views exposed forms and Webform that use information already available through Drupal's Form API to add declarative WebMCP metadata to existing interfaces. WebMCP remains experimental, with its current specification published as a W3C Community Group Report rather than a W3C standard or Standards Track specification.

The browser-side approach differs from Drupal's existing MCP Server work. Declarative WebMCP makes forms already rendered in the browser easier for an agent to understand as structured tools, while MCP Server allows external MCP clients to work with Drupal capabilities without operating through the site's interface. Te Brake identifies Tool API as a possible connection between the two approaches, where the same Drupal operation could potentially be exposed through MCP Server and imperative WebMCP, but he has not yet demonstrated that path in code.

A Webform reservation experiment compared the same task with and without WebMCP using the same model, browser, viewport, and starting state. Both runs successfully saved all eight requested values, while the agent used three tool calls with WebMCP instead of six without it and finished in 20.9 seconds compared with 50.1 seconds. Total input across the run was 54% lower with WebMCP, although the difference in uncached input was about 11%. The run without WebMCP also had to correct the date once, and Te Brake cautions that the comparison is an illustration rather than a benchmark. He plans further experiments with Tool API and more complex Drupal interfaces.