usage_by_bucket

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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds meaningful behavior beyond that: the return envelope structure, the truncation flag and its implications, and the warning not to present a truncated list as complete. It does not mention auth or rate limits, but those are less critical for a read-only usage tool.

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?

The description is front-loaded with purpose, then returns, then truncation warning, then args. It is appropriately sized, but 'in an envelope' is slightly redundant with the explicit return shape that follows, and the Args section repeats field names already in the schema.

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 and zero schema coverage, the description does the necessary work: it explains the return structure and truncation semantics, and documents both parameters. For a simple read-only tool, nothing essential is missing, though the absence of sibling context keeps it short of perfect.

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%, so the description carries the full burden and does so adequately: it explains limit as maximum rows with a default of 25, and target as a MinIO target name from config that can be omitted for the default. It fully covers both parameters with no obvious missing meaning, though it could specify what targets are available.

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 states a specific metric (per-bucket usage in bytes and objects), ordering (biggest first), and delivery format (envelope). It clearly identifies the resource and measurement but does not distinguish this tool from similar siblings such as bucket_info or capacity_rca.

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?

There is no explicit guidance on when to use this tool versus alternatives like bucket_ls or capacity_rca. The only conditional instruction is about omitting target for the default, which is parameter usage rather than tool-selection guidance.

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