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

Annotations declare readOnlyHint=false, openWorldHint=true, idempotentHint=true and destructiveHint=false, and the description usefully explains why a "read" is not read-only: it refreshes TikTok details when the cached record is stale. It also warns that public targeting data cannot establish effectiveness or sensitive traits, adding interpretive context. It does not cover auth or rate-limit behavior.

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 tight sentences with the core action front-loaded and no filler. The second sentence is dense and slightly cryptic ("sensitive traits") but still short and purposeful.

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 not be described, and annotations already carry the safety profile. The description supplies the two things structured data can't: the refresh side effect and the data-interpretation caveat. Only the undocumented parameter meanings leave a gap.

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% for both required params, so the description must carry the semantic burden, and it does not: nothing says what brandId or adId identify, or that adId must reference an already-saved ad. Only the generic phrase "saved public ad" hints at adId's role.

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 verb and resource ("Read a saved public ad") and adds the refresh-if-stale side effect, which cleanly separates it from search_library_ads (plural, query-driven) and save_library_ad. It does not explicitly name a sibling, so it stops short of 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?

Usage is implied by "read a saved public ad," but there is no explicit when-to-use vs. search_library_ads / analyze_library_ad guidance or any exclusion. The closing caveat about public targeting data is a data-interpretation warning, not tool-selection guidance.

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