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

With no annotations, the description correctly carries the burden. It discloses the asynchronous behavior ('pending' while background recording is in progress), the eventual output (signed URL), and the cost profile ('Storage-only — costs no Meta API budget'). It does not cover error cases(such as TTL expiration or failure states), but the key behavioral traits are surfaced.

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?

Three short sentences, each adding distinct value: purpose (fetch clip after rendering), return states (signed URL vs pending), and cost/storage semantics. The key constraint is front-loaded; no filler exists.

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?

The description is complete for a simple three-parameter polling tool: it states prerequisite, expected return states, and cost characteristics. The absence of an output schema means some return-format detail would help, but the description already covers the essential 'pending vs ready' contract, so no critical guidance 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 coverage is 100%, so the input schema fully documents all three parameters. The description adds no detail beyond the schema (e.g., it doesn clarify format of ad_account_id or how ad_format maps to placements). Baseline 3 is appropriate because the schema already does the heavy lifting.

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 clearly states a specific verb ('Fetch') and resource ('animated placement-preview clip') and ties it to its render sibling ('previously rendered with adsap_get_ad_preview'). This makes its purpose unambiguous and distinguishes it from the many get/list siblings within the toolset.

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 prerequisite is explicit: the clip must have been previously rendered with adsap_get_ad_preview. The 'pending' status also implies it is used as a poll for an async background recording. It could have gone further and explicitly said 'use adsap_get_ad_preview when you want a static preview,' but the naming and prerequisite make the usage context clear.

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