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browser_get_css_styles

Inspect computed CSS styles and matched stylesheet rules for an element by CSS selector or @ref reference to debug styling issues.

Instructions

Inspect element computed CSS styles and matched stylesheet rules by selector or @ref.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
refNoElement reference from snapshot (e.g. '@1')
selectorNoCSS selector of element

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.8.0

TDQS

B3.1/5.0
Behavior2/5

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

With no annotations provided, the description carries the full behavioral burden. 'Inspect' implies a non-mutating read, but nothing states whether it requires a loaded page, what happens if the selector matches nothing, or whether it forces style recalculation. Key behavioral context is absent.

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?

A single front-loaded sentence with no filler: the capability comes first and the input modes follow. Nothing could be trimmed without losing meaning.

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?

For an inspection tool with no output schema, describing the return as 'computed styles and matched stylesheet rules' is a reasonable start, but the shape of that data (per-property values, which rule won, cascade info) is left undefined, and with no annotations the tool's safety/state profile is also unstated.

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%, so both params are already documented, and the baseline is 3. The description does add a small amount of value by framing ref and selector as alternative lookup modes rather than two independent inputs, but it adds no format details beyond the schema's '@1' example.

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 names a specific verb (inspect) and a precise resource (computed CSS styles and matched stylesheet rules), and it clarifies the two lookup modes. No sibling tool covers this exact capability, so an agent can place it confidently, though it never names or contrasts an adjacent tool.

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?

There is no when-to-use guidance, no prerequisites (e.g. page must be loaded, element must come from a prior snapshot), and no indication of when to prefer browser_eval or browser_get_html instead. The 'by selector or @ref' clause is input selection, not usage guidance.

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