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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety and retry profile is largely covered. The description adds two genuinely useful bits not in annotations: the compliance rule against copying claims/creative, and the practical instruction to reuse the idempotencyKey. It says nothing about whether the save is reversible or where the saved ad surfaces (list_saved_ads).

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 earning its place: purpose first, then the compliance constraint, then the idempotency instruction. The core action is front-loaded and there is no filler.

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 explanation, and annotations cover the mutation/idempotency safety profile. The description covers purpose, a compliance constraint, and retry behavior, which is enough for correct invocation; the missing piece is how this relates to the surrounding library tools (search/get/analyze/list_saved_ads).

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 the burden. It loosely touches all four parameters ('selected public ad' for adId, 'for this brand' for brandId, 'optional notes' for note, 'Reuse idempotencyKey'), but adds no format or syntax detail (UUID, pattern constraints, length caps) beyond what the schema already encodes structurally.

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 and resource combination: saving a selected public ad as inspiration for a brand, with optional notes. This is clearly distinguishable from get_library_ad, search_library_ads, analyze_library_ad, and delete_saved_ad. It stops short of naming a sibling or the upstream step that produces the ad, so it is clear but not maximally differentiated.

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 description implies the workflow (a public ad has been selected from the library) and gives one constraint ('Do not copy the advertiser's claims or creative'), but never states when to use this versus analyze_library_ad or get_library_ad, nor any prerequisite ordering. Usage is inferable but not explicit.

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