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

With no annotations, the description carries the full burden and does well: it explains that an alias has no password, seat, or storage of its own, that mail threads in the target box and counts against its storage, and that the number of aliases is capped. It does not mention permission requirements or what a successful response looks like.

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 dense but well-structured sentences with no filler; the core behavior is front-loaded before the operational constraints, and every clause adds information an agent would otherwise have to infer.

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 two-parameter, no-output-schema tool with full schema coverage, the description supplies the behavioral model (storage accounting, alias limits, no seat/password) that the structured fields lack. Missing only auth/permission expectations and return-value confirmation.

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%, with both 'alias' and 'address' fully documented including the refusal conditions and a support-queue exclusion. The description itself adds no parameter-level detail beyond what the schema already provides, so 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?

States a specific verb ('points another address at a mailbox') and the exact resource, with an explanation of the mechanism (mail lands, threads, counts against storage). It is clearly distinguishable from remove_mailbox_alias and from add_mailbox_holder, which creates a mailbox rather than an alias.

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?

The description directs the agent to list_mailboxes for the alias limit and current usage, which implies a check-before-add workflow, and the schema adds the constraint that a support queue is not a mailbox. There is no explicit when-not guidance or step-by-step prerequisite sequence.

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