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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description goes well beyond this by disclosing transient behavior (null imageUrl/videoUrl means the mirror job hasn't run — retry in ~5 minutes), time sensitivity (S3 URL TTL ~1 hour), structural variance (DCA variants when hasDca: true), and error semantics (404 enrollment caveat). No contradiction with annotations.

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?

Four dense sentences, each earning its place: scope of return, prerequisite sequencing, null/retry behavior, DCA special case, and 404 error routing. The core purpose is front-loaded in the first sentence, and there is zero filler or repetition of annotation data.

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, the description carries the burden of describing the response — and it does, naming all key fields (copy components, click URL, UTM params, imageUrl/videoUrl, hasDca/dca). It also covers error semantics (404), transient states (null URLs), and prerequisites. For a 2-parameter read-only tool, nothing an agent needs to call it correctly is missing.

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 100%, so the schema already documents both parameters adequately, warranting the baseline of 3. The description restates the adId sourcing guidance ('Use after nevent_list_paid_ads') that already appears in the schema's adId description, reinforcing but not adding substantial new parameter-level meaning.

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 states a specific verb and resource: 'Get the creative content of a specific ad' and enumerates the exact fields returned (copy, click URL, UTM params, pre-signed S3 URLs). This clearly distinguishes it from sibling tools like nevent_list_paid_ads (listing) and nevent_get_paid_ad_group_insights (ad groups/insights).

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?

Gives explicit sequencing guidance: 'Use after nevent_list_paid_ads to get a valid adId.' It also names a concrete alternative for a failure mode: 'A 404 may mean this tenant is not enrolled in the insights pilot — call nevent_paid_ads_health to confirm.' Both the prerequisite and the fallback are explicit, not left to inference.

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