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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds nothing beyond that: it doesn't say this is display-only, what the cards contain, or any limits on how many items can be rendered.

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?

One short sentence is concise but not earned conciseness – it is under-specification. Nothing is front-loaded because there is nothing substantive to front-load.

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?

An output schema exists, so return values needn't be described, and the input schema documents field types. But the item contract (which fields are required for a meaningful preview, how metrics are used) is left entirely unstated for a 4-parameter tool, so the definition is not complete for correct invocation.

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 0% across 4 parameters, including a nested items array with 13 fields (ad_name, headline, primary_text, cta, metrics, urls), and the description names none of them. With zero coverage and a nontrivial nested payload, the description must compensate and does not.

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?

"Show ads as preview cards" is essentially a restatement of the tool name and title, adding only the output form (preview cards). It gives no differentiation from siblings like render_ads_console or render_performance_report, leaving the agent unable to tell which renderer to pick.

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?

No when-to-use, prerequisites, or alternative is named. The description offers no signal about when preview cards are preferable to the other rendering tools in the family, so selection is left entirely to inference from the name.

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