capacity_rca

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

The readOnlyHint annotation already covers the safety profile, and the description reinforces it with a "[READ]" prefix. It adds real behavioral context beyond the annotation by disclosing the output shape (ranked findings, each with cause and suggested action) even though no output schema exists.

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?

Four tight sentences: purpose, when-to-call, what-it-aggregates, and the one argument. Front-loaded with the primary use case and no filler.

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 one optional parameter and no output schema, the description supplies the missing return-value information (cause + suggested action per ranked finding) and the parameter's source/omission behavior. Nothing an agent needs to call it correctly is 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 carries the full burden for the single parameter, and it does: "MinIO target name from config; omit for the default." That supplies both the value source and the omission semantics, matching the schema's null default.

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 (capacity & usage RCA) and enumerates exactly what it folds together: capacity vs used, offline drives/nodes, per-drive hotspots, imbalance. That scope clearly separates it from point-read siblings like usage_by_bucket, drive_status, and cluster_status.

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?

"Call this first on any 'storage is filling up / writes are failing' question" gives an explicit trigger condition and an ordering rule relative to siblings. It stops short of naming which sibling to fall back on for narrower questions, so it is clear context rather than full when/when-not routing.

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