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

Goes beyond the readOnly/openWorld annotations by explaining the EU-disclosure coverage rule and that non-covered fields return null rather than being inferred — valuable, non-obvious data-quality context. It also discloses the 1-credit cost, which annotations do not carry. Missing: any note on caching behavior or failure modes.

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 tight sentences, front-loaded with purpose and followed by the coverage caveat and cost. The opening 'Ad details.' largely restates the title, but it costs almost nothing and the rest is dense and waste-free.

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 no output schema and only two params, the description covers the important unknowns: what fields come back, when they will be null, and the credit cost. The main omission is routing guidance against linkedin_adsSearch.

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 50% — the url parameter is documented in the schema while cache_max_age is undocumented in both places. The description adds nothing about either parameter (no URL format hint, no cache semantics), so it neither compensates for the gap nor improves on what the schema already says.

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+resource: 'One ad from LinkedIn's public Ad Library' with the fields returned (creative, copy, advertiser, paying entity). The word 'One' implicitly contrasts with the linkedin_adsSearch sibling, but the sibling is never named, so differentiation depends on inference.

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 single-ad framing implies this is a detail lookup rather than a discovery call, but the description never says when to use it versus linkedin_adsSearch, or that you need an ad URL/id from a prior search. Usage is implied, not stated.

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