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

Annotations declare destructiveHint=true but the description adds genuinely non-structured behavior: rules are applied with !important to survive the site's runtime, and an empty string reverts a property to the original design. That revert semantics materially softens the destructive picture and is exactly the context the annotation cannot convey.

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?

Two sentences: the first front-loads the operation and scope, the second covers the runtime override and the revert escape hatch. The property enumeration earns its place by hinting at accepted value families; no filler.

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?

For a destructive mutation with no output schema, this covers the essential behaviors (override persistence, revert path, single-element blast radius). It stops short of stating failure modes or that scope defaults to the current route, which is left to the schema.

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 67%; the description adds meaning for `css` beyond the schema by explaining the empty-string/clear behaviour, which the schema does not mention. It does not clarify `scope` (page vs site) or the key/tag/route relationship, but the added css semantics are real value.

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 and resource ('Set CSS on one element') and enumerates the property families it governs, which clearly separates it from siblings like edit_text or batch_edit_design. An agent can tell what this does without opening the schema.

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?

Usage is implied by the single-element framing and the empty-string revert tip, but there is no explicit when-to-use guidance versus batch_edit_design or edit_text, nor any prerequisite or exclusions. Adequate but with a clear gap.

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