styles

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds minimal behavioral context (the 'facts behind a visual diff' framing) but does not disclose how limit or props affect results, nor any edge cases like empty selector matches. It does not contradict annotations.

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

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

A single, tightly written sentence that front-loads the core purpose with zero filler. It is concise and structured well for quick comprehension.

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

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

While the tool is simple and an output schema exists, the description fails to explain the limit and props parameters, which are essential for correct invocation. Without schema descriptions, the agent lacks enough context to use the tool properly. The core purpose is clear, but parameter semantics are incomplete.

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

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

Schema coverage is 0%, so the description must clarify parameters. It only explains 'selector' as a matching mechanism, but gives no meaning for 'limit' (number of elements) or 'props' (which CSS properties to return). An agent would be left guessing on those two parameters.

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

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

The description clearly states the tool returns computed styles for elements matching a selector, with a specific use case ('the facts behind a visual diff'). It is a distinct action from siblings like page_state or screenshot, and the verb+resource combination is unambiguous.

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

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

The description implies a use case (visual diffing) but provides no explicit guidance on when to prefer this tool over alternatives like page_state or read_js. No exclusions or comparative context are given, so an agent must infer when it is appropriate.

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