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

Annotations already declare readOnlyHint/destructiveHint, so the bar is lower, yet the description adds value by disclosing a behavioral trait annotations cannot: the metric relies on a 30-day cached velocity, which warns the agent that the stock-out signal is lagging, not real-time. It omits permission requirements or response-shape details.

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?

Front-loads 'READ-ONLY', then the operation, then the user questions. Three compact sentences with minimal waste, though the two quoted example phrasings are somewhat redundant with the preceding clause.

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?

There is no output schema, so the description must carry more of the return-value burden; it hints at a list of at-risk ad-product overlaps but does not describe the shape, fields, or pagination. For a diagnostic tool it is adequate but leaves the agent guessing about the result format.

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 67%, and the description adds no parameter-level meaning. days_threshold's default and intent are already in the schema, account_id is documented inline, but profile_id is undocumented in both schema and description. Baseline 3 is appropriate since the description does not compensate for the partial coverage gap.

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 (cross-references) over two named resources (catalog days of cover and active SP product ads) and delivers the analytical output ('finds where you are paying for clicks on products close to stock-out'). This is clearly distinguishable from sibling list/CRUD tools like ads_list_sp_product_ads or ads_get_budget_usage.

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?

Provides concrete triggering questions ('am I wasting ads budget?', 'are ads pushing products that are running out?') that map well to the tool's purpose. It gives clear context for use but names no alternatives or explicit when-not conditions (e.g., no mention of ads_catalog_coverage as a related diagnostic).

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