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Chrome Bridge

Chrome Bridge

by frsorrentino
OverviewSchemaSourceRelated ServersDiscussionsAdmin
JavaScript
Local

hover

Idempotent

Move the mouse pointer over an element by CSS selector or ref to trigger JS pointer handlers; trusted mode moves the real pointer so CSS pointer-over styles apply.

Instructions

Hover over an element, by CSS selector or ref. Default: synthetic mouseenter/mouseover/mousemove, which fire JS hover handlers but not CSS :hover. trusted moves the real mouse pointer (chrome.debugger), so CSS :hover rules and their transitions apply.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "hover"
  }
}

Input Schema

NameRequiredDescriptionDefault
refNoFrom get_interactives
tab_idNoTarget tab; omitted = last tab navigated in this session, else the active one
trustedNoReal browser pointer via chrome.debugger, main frame only: needed for CSS :hover
frame_idNoTarget iframe id from get_frames; omitted = main frame
selectorNoCSS selector; ">>>" pierces shadow DOM

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv1.28.0
    • changedInput schema / properties / selector / description
      Previous value: -"CSS selector; \">>>\" pierces shadow DOM. Triggers CSS and JS hover handlers"New value: +"CSS selector; \">>>\" pierces shadow DOM"
    • addedInput schema / properties / trusted
      Added value: +{
+  "default": false,
+  "description": "Real browser pointer via chrome.debugger, main frame only: needed for CSS :hover",
+  "type": "boolean"
+}
  2. Changed3 schema fields changedv1.10.0
    • addedInput schema / properties / frame_id / description
      Added value: +"Target iframe id from get_frames; omitted = main frame"
    • addedInput schema / properties / selector / description
      Added value: +"CSS selector; \">>>\" pierces shadow DOM. Triggers CSS and JS hover handlers"
    • addedInput schema / properties / tab_id / description
      Added value: +"Target tab; omitted = last tab navigated in this session, else the active one"
  3. First observedv1.8.0

TDQS

A4.4/5.0
Behavior4/5

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

Beyond the annotations (readOnlyHint=false, destructiveHint=false, idempotentHint=true), the description discloses the non-obvious behavioral distinction: synthetic events fire JS handlers but not CSS :hover, while trusted drives the real pointer via chrome.debugger so CSS transitions apply. It does not cover failure modes or return behavior, but it discloses the trait that actually matters here.

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?

Two sentences, front-loaded with the action and addressing modes, then the mode semantics. Every clause earns its place with no filler.

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?

For a single-action interaction tool with full schema coverage and no output schema, the description is nearly complete: it covers addressing, modes, and the main-frame limitation (though that also appears in the schema). Return/error behavior is not described, a minor gap for a hover action.

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

Parameters4/5

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

Schema coverage is 100% and each param carries a description, so the baseline is 3. The description adds real meaning for the trusted flag, explaining the mechanism (chrome.debugger) and the consequence (CSS :hover applies), which is more than the schema's terse wording conveys.

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

Purpose5/5

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

States a specific verb (hover) and resource (an element), plus the two addressing mechanisms (CSS selector or ref). An agent can distinguish this from siblings like click or move it easily without opening the schema. It is a clean verb+resource statement.

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

Usage Guidelines4/5

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

Gives clear guidance on when to choose the trusted mode (when CSS :hover rules and their transitions matter), which is the primary usage decision for this tool. It does not name alternative tools or explicit when-not conditions, but the mode-selection guidance is concrete and actionable.

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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