System metrics

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful context beyond that: values are a "point-in-time sample with a UTC timestamp," which tells the agent the data is a snapshot rather than a time series and how to interpret the timestamp. Missing only things like sampling latency or permission requirements.

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: the returned metrics are front-loaded, the optional parameter follows, and the sampling semantics close it out. No filler or redundant restatement of the name.

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?

An output schema exists, so return values need not be fully documented, yet the description still names the key fields. Combined with the snapshot/timestamp semantics and the parameter explanation, this is nearly complete; only minor operational details (units, cost/latency) are absent.

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 0%, so the description must carry the burden for the single optional boolean. It does so explicitly: setting include_disk adds root-volume usage. The only gap is that it doesn't restate the default (false), which the schema already supplies as default=false.

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 ("Report host health") and enumerates exactly what is returned: CPU utilisation, logical core count, 1-minute load average, memory usage, plus optional root-volume usage. An agent knows precisely what this tool produces without opening the schema.

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 — the framing "host health" and the point-in-time nature suggest quick inspection rather than historical trending, and include_disk is described as an opt-in extra. There are no sibling tools to route against, but the description never explicitly says when to reach for this versus another diagnostic approach, nor any exclusions.

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