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

Annotations already cover readOnly/destructive/openWorld, so the bar is lower, and the description still adds real context by defining the non-obvious 'went_nowhere' metric as scans that reached the product with no destination. It leaves out other behavioral facts an agent would want, such as whether the breakdowns are always returned and how time windows aggregate.

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?

Two sentences, front-loaded with what is returned and followed by a gloss on the one metric that needs it. The 'went_nowhere' explanation is narrative but earns its place because the term is otherwise opaque; minor tightening possible.

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?

The existence of an output schema means return values need not be explained, and the annotations cover the safety profile. However, the description promises breakdowns 'by country, device, link type and batch' while the schema exposes no grouping controls, leaving it ambiguous whether those are fixed facets or optional, and it omits the time-window parameter entirely.

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 carries the full burden, yet it says nothing about either parameter. 'days' (default 30, max 365) is never mentioned, so an agent gets no signal about the lookback window, and 'gtin' format/expectations are only indirectly hinted at by 'one GS1 product'.

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 ('Scan counts for one GS1 product') and enumerates the breakdown dimensions (country, device, link type, batch). The scope 'one GS1 product' implicitly separates it from the sibling get_scan_stats, but the description never names or contrasts that alternative outright.

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?

Usage is only implied by the scoping phrase 'for one GS1 product'; there is no explicit when-to-use or when-to-prefer-get_scan_stats guidance despite that sibling clearly overlapping. No prerequisites, no exclusions, no mention of when the breakdown dimensions matter.

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