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Cloudflare Playwright MCP

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by cloudflare

browser_drag

Destructive

Enable drag and drop interaction between two web elements using precise references for automated browser testing with Cloudflare Playwright MCP.

Instructions

Perform drag and drop between two elements

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
endElementYesHuman-readable target element description used to obtain the permission to interact with the element
endRefYesExact target element reference from the page snapshot
startElementYesHuman-readable source element description used to obtain the permission to interact with the element
startRefYesExact source element reference from the page snapshot

Implementation Reference

  • Handler function implementing the browser_drag tool logic: resolves locators from snapshot, generates code snippet, and performs dragTo action.
    handle: async (context, params) => {
      const snapshot = context.currentTabOrDie().snapshotOrDie();
      const startLocator = snapshot.refLocator({ ref: params.startRef, element: params.startElement });
      const endLocator = snapshot.refLocator({ ref: params.endRef, element: params.endElement });
    
      const code = [
        `// Drag ${params.startElement} to ${params.endElement}`,
        `await page.${await generateLocator(startLocator)}.dragTo(page.${await generateLocator(endLocator)});`
      ];
    
      return {
        code,
        action: () => startLocator.dragTo(endLocator),
        captureSnapshot: true,
        waitForNetwork: true,
      };
    },
  • Input schema definition for browser_drag tool using Zod, specifying start/end elements and refs.
    schema: {
      name: 'browser_drag',
      title: 'Drag mouse',
      description: 'Perform drag and drop between two elements',
      inputSchema: z.object({
        startElement: z.string().describe('Human-readable source element description used to obtain the permission to interact with the element'),
        startRef: z.string().describe('Exact source element reference from the page snapshot'),
        endElement: z.string().describe('Human-readable target element description used to obtain the permission to interact with the element'),
        endRef: z.string().describe('Exact target element reference from the page snapshot'),
      }),
      type: 'destructive',
    },
  • src/tools.ts:46-46 (registration)
    Registers browser_drag by spreading tools from snapshot.ts into the snapshotTools array.
    ...snapshot,
  • src/tools.ts:26-26 (registration)
    Imports the module containing browser_drag tool definition.
    import snapshot from './tools/snapshot.js';
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already indicate this is a destructive (destructiveHint: true), non-read-only (readOnlyHint: false) operation with open-world context (openWorldHint: true). The description adds that it performs drag-and-drop between elements, which provides some behavioral context, but doesn't elaborate on what 'destructive' means here (e.g., might change UI state) or any rate limits. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, efficient sentence that directly states the tool's purpose without any fluff or redundancy. It's appropriately sized and front-loaded with the core action.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the destructive nature (per annotations) and lack of output schema, the description is somewhat incomplete. It doesn't explain what happens after the drag-and-drop (e.g., UI changes, errors) or potential side effects. However, the high schema coverage and clear purpose make it minimally adequate for a basic interaction tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, with clear documentation for all 4 parameters (startElement, startRef, endElement, endRef). The description adds no additional parameter semantics beyond what's in the schema, so it meets the baseline of 3 for high schema coverage without adding value.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action ('Perform drag and drop') and specifies the resources involved ('between two elements'), which distinguishes it from siblings like click or hover. However, it doesn't explicitly differentiate from similar interaction tools like browser_select_option or browser_file_upload that might involve dragging in some contexts.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (like needing a page snapshot), nor does it specify scenarios where drag-and-drop is appropriate versus other interaction methods like clicking or typing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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