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

The description frames this purely as a lookup ('Find ... by name', 'returns IDs'), i.e. a read operation against an external public library, yet annotations declare readOnlyHint=false. That mismatch directly misleads an agent about whether the call mutates state. The description also omits any side-effect, auth, or rate-limit context that would reconcile the non-read-only annotation.

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?

Two tightly written sentences with the purpose front-loaded and no filler; the second sentence adds usage/return context. 'Uses an available public ad library' is slightly vague but does not waste much space.

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?

An output schema exists, so return values need no prose, and the annotations cover the safety flags. Still, the required brandId parameter is undocumented and the read/write ambiguity is left unresolved, so the description is only minimally adequate for a 3-required-param tool.

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 carry parameter meaning. It maps 'Meta or TikTok' to the source enum and 'by name' loosely to query, but the required brandId is never mentioned in either the schema or the description, and constraints like maxLength=50 or the brandId pattern are unexplained.

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?

States a specific verb (Find) plus resource (public Meta or TikTok advertisers) and the lookup key (by name), so an agent can tell this apart from ad-level siblings like search_library_ads or discover_brand_profile. It does not explicitly name a sibling it is not, which keeps it from a 5.

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?

'returns IDs for a user-selected watch' implies the downstream workflow (feed IDs into create_ad_watch), giving implied usage context. However, there is no explicit when-to-use/when-not statement and no named alternative (e.g., search_library_ads) for the agent to route between.

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