get_css_styles

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

Annotations only cover the safety profile (readOnly/idempotent/non-destructive). The description goes well beyond: it discloses that output is scoped to the first selector match, that opaque cross-origin stylesheets are listed by href only, and which CSS features (user-agent styles, @container, @scope) are not evaluated — real behavioral caveats an agent needs.

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?

Information-dense and front-loaded: the purpose sentence comes first, followed by the distinctive comparison, then caveats, then the parameter note. Slightly long with heavy parenthetical enumeration, but nearly every clause carries signal.

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?

There is no output schema, and the description compensates by describing the return shape (per-property winning declaration with selector, stylesheet, rule position, importance, layer, media, plus overridden declarations). Combined with the disclosed evaluation limits, an agent has what it needs to call and interpret the tool.

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 description coverage is 100%, so all five parameters are already documented in the schema (shadow-DOM piercing, frame/tab defaults, inherited handling). The description only restates that 'properties narrows the output', adding no syntax or format detail beyond the schema; baseline 3 applies.

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?

States a specific verb+resource — resolving which CSS declaration wins for an element — and immediately contrasts it with query_dom ('query_dom gives the computed value, this gives who set it'). An agent can route between the two without opening schemas.

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?

Explicitly names the sibling alternative and the deciding criterion (computed value vs. originating declaration), and enumerates when the tool will not deliver useful results: cross-origin sheets without CORS, user-agent styles, @container and @scope.

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