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

Annotations already establish that the tool is read-only, idempotent, and non-destructive. The description adds that results are active ad creatives and lists return fields, but it does not disclose pagination behavior, rate limits, or the nuance that status can be INACTIVE/ALL despite the 'active' wording.

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?

The description is one front-loaded sentence with the action, resource, and output fields, followed by a compact example call. It contains no filler or repetition, and every sentence 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?

With no output schema present, the description compensates by enumerating the returned fields: advertiser page, ad body text, media, platforms, run dates, and active status. The example shows required parameters, and all input parameters are fully described in the schema, so nothing essential is missing.

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 the input schema already documents all parameters such as query, status, country, and media_type. The description adds a useful invocation example, but it does not provide parameter semantics beyond what the schema already supplies.

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 states a specific action ('Search'), a specific resource ('Facebook / Meta Ad Library'), and the returned content ('advertiser page, ad body text, media, platforms, run dates, and active status'). Naming the Meta Ad Library clearly distinguishes it from sibling scraper tools for Instagram, TikTok, and YouTube.

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 gives clear context for when to use the tool: when searching the Meta Ad Library by keyword or advertiser. The example further clarifies invocation, but it does not explicitly name alternative tools or state when not to use it, so it stops short of full guidance.

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