preview_ad

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

Annotation contradiction: the description says the tool 'save[s]' a PNG under a directory, which is a filesystem write, while annotations declare readOnlyHint=true. Per the scoring rule, a description that contradicts an annotation receives 1.

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 efficient sentence that front-loads the action, target, and output, then adds the destination and default path. Every clause earns its place.

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 does not say what the tool returns (file path, success, PNG data?). It covers enough for a one-parameter tool, but return behavior and ad_id semantics are gaps.

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%, so the description must compensate, but it never explains the single required ad_id beyond the schema title 'Ad Id'. The parameter is self-evident enough to guess, but provenance/format information is missing.

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 names a clear action and resource: 'Render a sponsored-message preview PNG for chat' plus the save location. It is more specific than a generic 'preview an ad', though it doesn't explicitly distinguish itself from sibling tools like check_ad_post or launch_ad.

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?

'for chat' gives an implied use case, but there is no explicit when-to-use / when-not-to-use guidance and no alternative sibling tool names. An agent must infer that this is for obtaining a PNG preview before launch.

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