drive_status

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

With only readOnlyHint=true from annotations, the description carries the rest and does so well: it discloses the exact return shape, the sort order, and a critical interpretation rule that a non-null 'error' means the metrics scrape failed rather than a healthy empty fleet. That last point is exactly the kind of failure-mode context an agent cannot get 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?

Front-loaded purpose sentence, then return contract, then the caveat, then args - a sensible ordering with little waste. The '[READ]' prefix is slightly redundant against readOnlyHint=true, but it is a single token and the rest of the text 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?

There is no output schema and only one annotation, so the description must explain returns - and it does, down to the keys and the error semantics. Combined with the parameter definition, an agent has everything needed to call and interpret this 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?

Schema description coverage is 0% for the single 'target' parameter, so the description must compensate and it does: it defines target as the MinIO target name from config and states the omit-for-default behavior. That is complete semantic coverage for a one-parameter tool.

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 resource and scope: per-drive rows with the fields returned (server, drive, used ratio) and the ordering (fullest first). This implicitly separates it from node_status, cluster_status and fleet_overview, which operate at coarser granularity. It does not name those siblings explicitly, 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?

Usage is implied by the 'fullest first' ordering and the warning about interpreting an empty list, which tells the agent the intended use case is capacity checking. However, no alternative tool is named and there is no when-not guidance, even though capacity_rca and usage_by_bucket are plausible substitutes for capacity questions.

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