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

Annotations already establish readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuinely non-structured context: results mirror what the platform's ad group / ad squad drawers show, and each id set maps to a specific plan field (e.g. tiktok.adgroup_settings.interest_category_ids). It says nothing about pagination or result volume, which is the remaining gap.

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 first two sentences are near-duplicates ('TikTok and Snapchat targeting choices...' repeated with minor rewording), wasting the most prominent position on redundant text. The remainder is dense but front-loaded usefully, packing platform-to-field mappings into a compact form.

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?

For a five-parameter, three-required lookup tool with no output schema and rich annotations, the description covers purpose, the alternative tool, and how returned ids are consumed. Minor gaps remain around result shape and whether an empty list is possible, but nothing an agent needs in order to call it correctly 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 80% and already explains type, search, country and ad_account_id, so the baseline is 3. The description earns above baseline by mapping each type to the destination plan field, which is information the schema does not contain and which directly determines how the caller uses the returned ids.

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 specific resource (TikTok and Snapchat targeting choices: interests, behaviors, languages, countries) and a specific verb (list, as the app's drawers list them). It explicitly distinguishes itself from the sibling search_targeting, which handles Meta targeting, so an agent can route between the two without opening a schema.

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?

It gives a clear selection rule for the main alternative: Meta targeting goes to search_targeting, everything TikTok/Snapchat comes here. It also ties usage to the downstream step ('the plan field their ids go in'), but it does not state prerequisites or exclusions among its own type values beyond what the enum already says.

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