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Chrome Bridge

Chrome Bridge

by frsorrentino
OverviewSchemaSourceRelated ServersDiscussionsAdmin
JavaScript
Local

modify_dom

Idempotent

Edit attributes, classes, styles, or text of a live DOM element. Changes are temporary and vanish on reload.

Instructions

Change an element in the live DOM: setAttribute, removeAttribute, addClass, removeClass, setStyle, setTextContent. Nothing is persisted — the next reload restores the page as the server sends it. For styling many elements at once inject_css is one call instead of N.

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": {
      "selector": "<selector>",
      "action": "<action>"
    },
    "name": "modify_dom"
  }
}

Input Schema

NameRequiredDescriptionDefault
nameNoAttribute name
valueNoAttribute value, style declaration, or text, per action
actionYessetStyle takes a CSS declaration in value; addClass/removeClass take className
tab_idNoTarget tab; omitted = last tab navigated in this session, else the active one
frame_idNoTarget iframe id from get_frames; omitted = main frame
selectorYesCSS selector; ">>>" pierces shadow DOM. Only the first match is changed
classNameNoClass to add or remove (addClass/removeClass)

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed6 schema fields changedv1.10.0
    • addedInput schema / properties / action / description
      Added value: +"setStyle takes a CSS declaration in value; addClass/removeClass take className"
    • addedInput schema / properties / className / description
      Added value: +"Class to add or remove (addClass/removeClass)"
    • 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. Only the first match is changed"
    • addedInput schema / properties / tab_id / description
      Added value: +"Target tab; omitted = last tab navigated in this session, else the active one"
    • addedInput schema / properties / value / description
      Added value: +"Attribute value, style declaration, or text, per action"
  2. First observedv1.8.0

TDQS

A4.2/5.0
Behavior4/5

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

Annotations indicate idempotent and non-destructive. Description adds transparency that changes are not persisted across reloads and that only the first match is modified. No contradictions 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?

Two concise sentences plus a one-sentence alternative recommendation. No redundant information; every sentence adds value.

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?

Given the 7 parameters fully described in the schema, no output schema, and annotations providing safety profile, the description adequately covers core functionality and persistence behavior. Could enhance by contrasting with query_dom for read-only access.

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 coverage is 100% with descriptive parameter names and descriptions. The description does not add additional context beyond the schema, so baseline score of 3 is appropriate.

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?

The description clearly states the tool changes an element in the live DOM, enumerates specific actions (setAttribute, removeAttribute, etc.), and contrasts with inject_css for bulk styling. It differentiates itself from sibling tools like inject_css.

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?

Explicitly states when to use inject_css instead for many elements, providing clear guidance. Does not explicitly exclude other scenarios, but the contrast is sufficient for most use cases.

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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