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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral context beyond them: returned definitions and dates bound the measured scope, and unmeasured domains yield no accessibility finding. It still says nothing about the shape or size of the aggregate result.

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 tight sentences with the core action front-loaded and no filler. The second sentence is denser and slightly telegraphic ('definitions and dates delimit the measured scope') but it earns its place by adding scope semantics.

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 should carry more of the return-value burden for an aggregate report. It hints at scope-bounding and null-finding behavior for unmeasured domains, which helps, but leaves the actual contents, granularity and response shape 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?

The tool takes zero parameters (empty schema, 100% coverage), so there is nothing for the description to disambiguate; baseline 4 applies. No parameter-level claims are made or needed.

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 states a specific verb ('Read') and resource ('aggregate public measurement summary and coverage'), which is clear. It distinguishes itself implicitly from siblings like voidly_incident_detail and voidly_incident_stats by being the aggregate summary, but never names or contrasts those alternatives explicitly.

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 word 'aggregate' and the sibling set (country/incident detail and stats), suggesting this is the high-level rollup. There is no explicit 'use this when...' or 'for per-incident breakdown use X instead' guidance, leaving the agent to infer the routing.

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