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

Annotations already declare readOnlyHint, idempotentHint and a closed world, so safety and repeatability are covered. The description adds one genuinely useful behavioral trait beyond that: the results are a period-over-period comparison against an equal-length preceding window, which an agent could not infer from the schema. It still says nothing about aggregation level or result shape.

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 dense sentence with no filler, and the comparison-period constraint is stated up front. It is packed tightly but every clause (the window relationship and the metric list) earns its place.

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?

With no output schema, the description usefully enumerates the returned metrics, which compensates for that gap, and all four parameters are optional and fully documented in the schema. What remains missing is routing guidance relative to the four sibling analytical tools.

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%, and every parameter (to, from, mode, project_id) has clear inline documentation including defaults, so the baseline is 3. The description adds no parameter-level meaning beyond the schema, which is acceptable here because the schema already carries the burden.

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 resource (age-check outcomes) and enumerates the exact metrics returned (checks, pass rate, fail rate, no-answer rate, time to result), so an agent knows precisely what this tool produces. However, it draws no boundary against siblings like get_breakdown or get_timeseries, so an agent must infer which one fits.

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 description states what the tool returns but never says when to prefer it over get_breakdown, get_failure_breakdown, get_funnel or get_timeseries. Usage is only implied by the word 'summary,' and no prerequisites or exclusions are given.

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