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

Annotations already declare a safe, idempotent read; the description adds what is actually being counted (every kept version, table row, bundle version, and trash until purged), how workspace ownership rolls up ('a workspace counts toward its owner'), and the null-means-no-limit convention. It also discloses authorization behavior and the FORBIDDEN failure mode, which annotations cannot express.

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?

Single front-loaded paragraph that leads with purpose and permissions before enumerating counted resources. It is dense and mostly earns its length, though the run-on listing of byte categories could be trimmed since an output schema already documents the response.

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 an output schema present, the description needn't itemize return fields, yet it does so usefully; permissions and counting semantics are fully covered. The remaining gap is the undisclosed volume of 'largest artifacts' returned and any aggregation/pagination behavior for large accounts.

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 100% and both param descriptions already state slug/id, alias, membership restriction, admin-only access, and the 'Not with team' exclusion. The description largely restates those constraints; the only additive nuance is that the account param accepts an alias and that the caller's own account is the 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?

Opens with a specific verb+resource ('Read storage usage') and immediately scopes the targets: own account, a team, or (for admins) another account. No sibling tool covers storage accounting, and the description makes the resource unmistakable without opening the schema.

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?

States the three usage modes (self by default, team membership, admin-only account) and the FORBIDDEN outcome for unauthorized callers, which is real routing guidance. It does not explicitly name an alternative tool to use instead, but no sibling overlaps, so the only real guidance gap is the unstated default when both params are omitted.

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