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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description contributes the one thing annotations cannot: what data comes back (plan, active share count, storage used). It stops short of stating scope (account vs workspace), units, or whether storage is a limit or a current value, which matters for a quota-checking 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?

It is a single short fragment with zero padding, but it is not front-loaded with an action and reads as an unfinished sentence. Brevity here crosses into under-specification rather than efficient structure.

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, the description carries the burden of explaining the return value, and it names the three fields it returns — which is the minimum needed. It omits the response shape, whether values are absolute or relative to a limit, and the account/workspace scope, so an agent cannot fully predict the payload.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The schema is an empty object and requires no explanation.

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 is a noun phrase listing three data points (plan, active share count, storage used) rather than a verb+resource statement, so the agent must infer the action from the name 'get_usage'. It is specific enough to distinguish this as the account-level usage read from siblings like get_share or list_shares, but the missing verb leaves the purpose implied rather than stated.

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 when-to-use guidance, no mention of alternatives, and no conditions or prerequisites. The agent can only guess that this is the tool for checking quota or plan limits from the returned field names; nothing explicitly routes it here versus list_shares for counting shares.

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