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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety and idempotency profile is fully covered by structured data. The description adds nothing behavioral beyond that – no note on aggregation window, how a unique user is counted, or data freshness. With annotations carrying the burden, a 3 is appropriate.

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?

A single front-loaded sentence with no filler, and the scope options are surfaced immediately. It is efficient, though it is arguably a touch sparse for an analytics tool with five parameters.

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 described, and annotations cover the safety profile; the schema covers all five parameters at 100%. What remains is the description stating the metric and scope, which it does. The one residual ambiguity – whether 'unique users' and 'unique scans' are synonymous – keeps it just short of a 5.

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 scope, dates and the idproject/idqrcode dependencies. The description only restates the scope choices, adding no format, default or dependency semantics beyond the schema. Baseline 3 is correct when the schema does the heavy lifting.

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?

Names a specific verb (Fetch) and resource (unique users / unique scans analytics) and enumerates the three scopes it operates over. This implicitly separates it from siblings like get_total_scans or get_account_scans by naming the 'unique' metric. It stops short of explicitly naming an alternative tool, so it is clear but not fully sibling-differentiated.

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 through the scope parameter (account/project/qrcode) and the tool name. There is no explicit statement of when an agent should prefer unique-user counts over total scans, nor any exclusions or prerequisites. This is minimum-viable guidance rather than genuine when-to-use direction.

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