BrowserMCP Extended

by NEO10111

Overview Schema Source Related Servers Discussions Admin

JavaScript

Local

browser_drag

Drag and drop between two elements by specifying source and target references from the latest snapshot.

Instructions

Perform drag and drop between two elements

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "startElement": "<startElement>",
      "startRef": "<startRef>",
      "endElement": "<endElement>",
      "endRef": "<endRef>"
    },
    "name": "browser_drag"
  }
}

Input Schema

Name	Required	Description
`endRef`	Yes	Target reference from the latest snapshot
`startRef`	Yes	Source reference from the latest snapshot
`endElement`	Yes	Human-readable target description
`startElement`	Yes	Human-readable source description

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Nov 2, 2026

TDQS

B3.1/5.0

Behavior2/5

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

With no annotations, the description carries the full behavioral burden and mostly fails it: it does not say this is a mutating, non-idempotent UI action, that it requires a fresh snapshot, or that it may fail silently if the drag is not supported. The single sentence only restates the action implied by the name.

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

Conciseness4/5

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

A single seven-word sentence, front-loaded with the verb and zero filler. It is efficient, though the brevity slides into under-specification rather than disciplined concision.

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

Completeness4/5

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

No output schema and no annotations exist to fill gaps, and the description supplies nothing about snapshot-ref freshness, whether intermediate hover steps are needed, or what a failed drag looks like. For a four-required-parameter UI mutation this is thin.

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% — all four parameters are documented in the schema as source/target human-readable descriptions plus snapshot refs. The description adds nothing beyond that, so the baseline 3 applies.

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?

States a specific verb ('drag and drop') and resource ('between two elements'), so the operation is unambiguous. However, it makes no attempt to distinguish itself from the sibling tool browser_drag_drop, which appears to do the same thing — a genuine risk of misselection.

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?

No guidance on when to use this tool, no prerequisites (e.g. that refs must come from the latest snapshot, or that the target may need to be scrolled into view), and no mention of the near-identical sibling browser_drag_drop as an alternative.

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