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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds meaningful context beyond them: 'LIVE' indicates freshness, 'from their official status pages' discloses provenance, and 'Deterministic: no model in the loop' assures the agent the result is computed, not generated. It stops short of a 5 because it doesn't mention failure modes such as unresponsive status pages or how the reliability index is scaled.

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 sentences with zero filler: the first delivers the core payload and freshness, the second gives usage triggers, and the third adds determinism plus sibling routing. The key metrics are front-loaded and every sentence 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?

For a simple tool (one optional param, no enums, no output schema), the description covers what is returned, the source, the time window, when to use it, and determinism. The only gaps are interpretive: the reliability index scale is not defined and no return shape is hinted, but with annotations carrying the safety profile and the tool being low-complexity, this is adequate with only minor omissions.

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 the single optional `provider` parameter is already fully documented as 'Optional. Filter to one provider by name.' The description reinforces the per-provider scope ('per cloud/SaaS provider') but adds no format, casing, or accepted-value detail beyond the schema, so the high-coverage 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 the exact resource (reliability index, incident count, median recovery time per cloud/SaaS provider) and the data source (official status pages), and scopes it to 'the current window.' It explicitly differentiates from siblings by declaring 'Prefer it over `answer`' and is clearly distinct from exploited_vulnerabilities and list_active_incidents.

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 explicit triggering conditions: 'Use for how reliable is X or which provider is more stable.' It also provides routing guidance against the sibling `answer`, telling the agent to prefer this tool for reliability queries, leaving no ambiguity about when to select it.

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