get_ad_previews

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

With no annotations, the description carries the full burden. It does disclose the read-only nature ('Get'), the return shape ('A dictionary containing preview iframe data'), and the all-placements behavior when ad_format is None. However, it omits error behavior, permissions, and edge cases, so transparency is only partial.

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 docstring-style layout front-loads the one-line purpose and uses compact, scannable Args and Returns blocks. The long placement enum is justified because the schema lacks an enum, and there is 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?

All three parameters are explained, the return type is stated, and an output schema exists so return documentation is optional. Remaining gaps are the lack of valid field-name enumeration, error-condition behavior, and usage guidance relative to the many sibling retrieval tools.

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%, but the description compensates fully: it explains ad_id, ad_format with a concrete placement list and default behavior, and fields with an example. This adds real meaning beyond the bare schema types and defaults.

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 first sentence states a specific verb and resource: 'Get preview iframes for an ad across different placements.' This clearly distinguishes it from siblings like get_ad_creative_by_id or get_ads_by_adaccount, which retrieve creative content or ad lists rather than iframe previews.

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 no guidance on when to use this tool instead of alternatives; the only contextual note ('If None, returns all available') describes ad_format behavior, not tool selection. No siblings are named and no exclusions or prerequisites are mentioned.

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