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

Annotations only declare readOnlyHint and openWorldHint, so the description carries the interpretive burden and does so well: it warns that last-probe time differs from fetch time and that community-path rows can be Voidly-operated and do not prove independent operators or accepted measurements. These are non-obvious semantic caveats an agent could not derive from the schema or annotations.

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?

Three dense sentences, front-loaded with purpose, then pagination, then interpretation caveats. Every clause carries information, though the phrase 'as bounded JSON pages' is slightly jargon-heavy and the by_domain reference assumes structure not documented elsewhere.

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?

There is no output schema, and the description does supply the key caveats needed to interpret results correctly (probe time vs fetch time, community-path provenance). It references by_domain rows and next_cursor without describing the returned shape, which is the remaining gap for a no-output-schema tool.

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?

With one parameter at 100% schema coverage, the baseline is 3, but the description adds traversal semantics the schema does not: start with no cursor, then follow next_cursor for each by_domain row. That is meaningful usage context beyond the schema's 'opaque next_cursor' note.

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 verb and resource with scope: 'Read rolling 24-hour raw probe metrics and lifetime Voidly evidence counters as bounded JSON pages.' An agent knows exactly what data class this returns. It does not explicitly differentiate itself from near-neighbors such as agent_relay_stats or get_measurement_freshness, so it falls short of a 5.

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?

Gives operational traversal guidance ('Start without a cursor; follow next_cursor for every by_domain row'), which is real usage instruction. However, it never says when to prefer this tool over the freshness/stats siblings, nor when not to call it. Usage is implied rather than contrasted against alternatives.

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