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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is fully covered externally. The description adds useful context (last-30-days default, POST-based group_by=date endpoint) but says nothing about result ordering, pagination interplay, or what happens when only one date bound is supplied.

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 purpose, followed by the endpoint/default rationale and the scope requirement. No filler; the only borderline sentence is the implementation note about POST/group_by, which is still informative for prediction of behavior.

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 no explanation, and annotations carry the read-only/idempotent profile. The description covers the default window and the key conditional requirement, leaving only minor gaps around date-range edge cases and pagination behavior that the schema partially addresses.

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 all seven parameters, making 3 the baseline. The note 'for scope=qrcode only idqrcode is required' adds a conditional nuance, but it sits in tension with the schema's idproject description ('Required when scope=project or qrcode'), so the net added value is limited.

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 and resource ('Fetch scan counts grouped by date') and names the three scopes it serves, which distinguishes it from the sibling grouping tools like get_scans_by_country/device/region. It does not, however, distinguish itself from get_account_scans / get_project_scans / get_qrcode_scans, which fetch scans at the same scopes without date grouping.

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 scope enum (account/project/qrcode) and the 'default date range: last 30 days' establish the operating context, and the final sentence implies usage for the qrcode scope. There is no explicit when-to-use guidance versus the numerous scan-related siblings, so the agent must infer selection from the scope argument alone.

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