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

readOnlyHint=true already establishes this as a safe read, lowering the burden. The description usefully adds that the output is daily-granularity series covering two specific metrics, but the trailing 'bunny.net: GET /storagezone/{id}/statistics' merely restates the endpoint and adds no behavioral context (pagination, rate limits, empty-zone behavior).

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 short sentences, front-loaded with what the tool returns; the endpoint reference is arguably redundant but costs almost nothing. No filler or hedging.

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, so the description must convey the return shape, and it does identify the two metrics and their daily resolution. A gap remains around series length, units, and behavior for a zone with no data, but the essentials are present for a read-only stats call.

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 100%, including the default-window rule for omitting both dates, so the schema fully carries parameter meaning. The description adds no additional parameter guidance, which is the correct baseline score when the schema does the heavy lifting.

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 names a specific resource (one storage zone) and the exact metrics returned (storage used, file count), so the agent knows what it gets. It does not, however, distinguish itself from the sibling bunny_get_statistics or bunny_get_storage_zone, leaving the boundary between these tools to inference.

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?

Scope ('for one storage zone') implies this is the per-zone variant of statistics, which is mild usage guidance, but there is no explicit when-to-use statement, no exclusion, and no pointer to bunny_get_statistics for account-wide data. The agent must infer the routing.

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