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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and a closed-world scope, so the safety profile is fully covered elsewhere. The description contributes the computation semantics (per-period new customers plus a cumulative running total), but says nothing about pagination, limits, or behavior on empty ranges.

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?

One sentence, front-loaded with the verb and the two metrics, with zero filler or redundancy. Nothing could be removed without losing meaning.

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?

For a simple read-only report with three fully documented parameters and no output schema, the description covers the key question an agent has: what the numbers represent. The gap is minor — it does not clarify whether the running total resets per groupBy bucket or spans the whole range.

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%: both date parameters are documented as ISO YYYY-MM-DD and groupBy carries a full enum with auto-detection noted. The description only echoes the date-range concept and adds no format or defaulting detail beyond the schema, so the baseline of 3 applies.

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?

The description names a specific resource and two concrete metrics: 'new customers per period' and 'the running total over a date range.' An agent knows exactly what data comes back, but nothing distinguishes this from the sibling report tools (get_revenue_report, get_expense_report), which have parallel naming.

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?

There is no when-to-use guidance, no exclusions, and no mention of the sibling report tools an agent might otherwise pick. The reporting use case is only inferable from the metric names in the description.

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