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

Even though annotations already declare readOnlyHint=true and destructiveHint=false, the description adds significant behavioral nuance: the split between dataCheckErrors (pre-submission koongo data check) and channelErrors (post-submission channel responses), the combined totals in errorCount/warningCount, and the async generation prerequisite. It also explains the source field values ('export' vs 'adapter'/'api_error') and the meaning of statusCounts vs listingStatusCounts. This goes well beyond the annotations and fully discloses report 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?

The description is long but dense: every sentence adds distinct information, from return shape to async behavior to field semantics. The opening sentence immediately states purpose, satisfying front-loading. It could be slightly better structured (e.g., bulletized return fields), but no sentence feels wasted.

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 fully documents the return structure including integrationId, errorCount, warningCount, statusCounts, listingStatusCounts, dataCheckErrors, and channelErrors, plus nested error and fixSuggestions fields. It also covers edge cases like project_id optionality and the need to poll ad_status. An agent has everything necessary to invoke the tool and interpret its result.

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 0%, so the description must carry all parameter meaning. It explains that ad_id is 'the id from list_ads' and that project_id is 'OPTIONAL (inferred for a single-project customer; project_id_required otherwise — then call list_projects).' This is exactly the kind of semantic routing information an agent needs, and it compensates fully for the empty schema descriptions.

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?

Description opens with a specific verb-resource pair: 'Get the validation report for one ad' with the scope 'aggregated errors and warnings that block or degrade its feed, with fix suggestions.' It explicitly distinguishes ads from marketplaces ('Ads are ads-based channels... not marketplaces'), which separates it from get_marketplace_report. The report content and groups are also clearly stated, leaving no ambiguity about what the tool returns.

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 provides strong contextual guidance on when the report is meaningful: 'Data-check errors exist only after a generation has run — finish the wizard, or repair_ad to (re)generate; export is async, so poll ad_status until productsRefreshing AND productsSubmitting are false, then read the report.' It also clarifies ads vs marketplaces, which helps choose between get_ad_report and get_marketplace_report. It does not explicitly contrast with get_ad_item_report or get_ad_item_history, so it stops short of a full 5.

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