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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful non-annotation context: Smart+ objects are a separate namespace invisible to the standard listing tools. It stops short of noting pagination or result volume, but the output schema exists to cover return shape.

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?

Front-loaded with verb and resource, then the sibling exclusion and the level enum. Two sentences, no filler, though the em-dash clause listing three resource types is slightly dense.

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 an output schema present, return values need no explanation, and annotations carry the safety profile. The one remaining gap an agent would want is the advertiser_id parameter's meaning, which neither the schema nor the description supplies.

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. It does document the meaningful enum values for level (CAMPAIGN | ADGROUP | AD), which the schema lacks, but says nothing about advertiser_id despite it being the other parameter. Partial compensation warrants a baseline 3.

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 uses a specific verb (Lists) plus the resource (Smart+ campaigns, ad groups or ads) and immediately contrasts it with the sibling listers list_tiktok_campaigns/adgroups/ads. An agent can distinguish this from every other TikTok listing tool 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 names the alternative tools and the exact condition that separates them ('these do NOT appear in list_tiktok_campaigns/adgroups/ads, which only cover standard (manual) objects') and states the intended purpose ('to see and report on Smart+ delivery'). That is explicit routing rather than implied usage.

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