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

Annotations only declare readOnlyHint=true, so the description carries the burden and it delivers: aggregation granularity rules (hourly, daily after 2 days, monthly after 40 days), the minimum range, and the notable caveat that uptime is not returned when grouping. These are non-obvious behaviors an agent cannot infer from structured fields.

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 paragraph that front-loads what is returned, then grouping, then temporal constraints, plus a compact endpoint reference. Every clause carries information, though the sentence is long and could be split for scannability.

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 does explain the returned metric set (uptime, apdex, timings, request counts), which is the key gap it must fill, and it flags the uptime/grouping interaction. It does not describe response shape or grouping result structure, leaving a small residual gap.

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 coverage is 100% (baseline 3), and the description adds real meaning on top: it explains that 'group' means by time bucket or by monitoring location/host, and that metric timings are in milliseconds. It does not restate the from/to format defaults already in the schema, which is appropriate.

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+resource ('Get aggregated metrics for one check over a time range') and immediately enumerates the metric families returned. It is clearly distinguishable from sibling read tools like updown_get_check (single check config) and updown_list_downtimes (event list).

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 concrete usage conditions: the range must span at least one hour, and grouping by 'time' or 'host' is optional. It does not name an alternative sibling (e.g. updown_get_check) or say when this tool is the wrong choice, so it stops short of explicit routing.

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