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

Annotations already flag destructiveHint=true, readOnlyHint=false and idempotentHint=false, so the safety profile is known. The description adds genuinely non-schema context: the permission tiers, that the private service credential is server-side only, and that passwords/message content are never returned — useful for a mutation tool. It does not, however, explain what the update destroys or whether quota reductions affect existing mail.

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?

Five short sentences, front-loaded with the operation and its scope before the permission and security notes. Little waste, though the closing security guarantees are somewhat boilerplate and repeat across the family.

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?

For a destructive update with no output schema and fully documented parameters, the description supplies the missing authorization and data-exposure context an agent needs. Counting on the schema for parameter detail and annotations for the destructive flag, the remaining gap is only the effect of a quota change on existing content.

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%, so all six parameters (including the plan-fitting constraints on quota_mb and files_quota_mb) are already documented in the schema. The description only echoes 'name or quota' and adds no syntax, units, or constraint detail beyond the schema, so the baseline 3 applies.

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 first sentence gives a specific verb and resource ('Change mailbox name or quota') and scopes it to the plan, which is enough to distinguish it from sibling mailbox tools like create/suspend/resume. It stops short of naming a sibling alternative, but the target resource is unambiguous.

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?

Usage is only implied: the description states the authorization model ('No guest access. Members can read. Owners, admins and organization keys can manage email'), which tells an agent who may call it but not when to choose it over mailbox_create or mailbox_suspend/resume. No exclusions or alternative routing are given.

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