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

Annotations already establish readOnly/idempotent/non-destructive/openWorld, so the bar is lower, and the description still adds non-obvious behavior: the read is executed through POST scans endpoints with group_by=device, plus the 30-day default window. It does not mention pagination behavior despite exposing page/per_page, but the added endpoint and default-range details are substantive.

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 short sentences, front-loaded with the action and grouping, followed by implementation and default-range notes. No filler, though the endpoint detail is marginally less important than the scope rules it follows.

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?

An output schema exists, so return values need not be explained, and annotations carry the safety profile. Scope rules, date defaults, and the required-id condition are all present; only the idproject/idqrcode requirement discrepancy leaves a small gap.

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 baseline is 3; the schema already documents every parameter including the date requirements. The description adds one dependency clarification ('for scope=qrcode only idqrcode is required'), though that statement sits in tension with the schema's idproject note claiming it is required for scope=qrcode as well.

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 (fetch), resource (scan counts), and grouping dimension (device platform), with the supported scopes spelled out. The grouping dimension implicitly separates it from siblings like get_scans_by_country or get_scans_by_date, but no sibling is named explicitly, so routing relies on the agent noticing the 'device' axis.

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 useful defaults ('Default date range: last 30 days') and a conditional requirement ('For scope=qrcode only idqrcode is required'), which is genuine usage context. However, it never says when to choose this tool over get_account_scans, get_project_scans, get_qrcode_scans, or the other group_by variants, so the choice is left to inference.

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