Crash rate

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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely non-structured context: that values are returned as fractions (0.01 = 1%) and that 7- and 28-day user-weighted aggregates are included, which prevents a units misreading. It omits auth requirements and data-freshness caveats, keeping it short of a 5.

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?

Two sentences, front-loaded with what is returned before the units caveat. Nothing is padded; each clause (source, granularity, aggregate windows, unit convention) carries distinct information.

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 sketches the return shape (daily values plus 7- and 28-day aggregates) and the unit convention. Full 100% parameter coverage plus rich annotations fill the remaining gaps; only freshness/latency of vitals data is left unstated.

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 every parameter (days, filter, dimensions, package_name) is already documented in the schema with examples. The description adds no parameter-level detail at all, so the baseline 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?

States a specific resource and its source clearly: daily crash rate from Android vitals via the Play Developer Reporting API. It distinguishes itself from non-vitals siblings by naming the exact metric, but gives no explicit contrast with near-neighbours like anr_rate or vitals_summary, which an agent must infer from names alone.

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 prerequisites, and no named alternative among the many vitals siblings (anr_rate, slow_start_rate, vitals_summary, vitals_by_version). Usage is only implied by the metric name; an agent gets no routing help between this and the aggregation tools.

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