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

With no annotations, the description carries the full burden and does disclose real behavior beyond the name: the grant is 'recorded' (audit trail), the holder list is visible to everyone on the box, and a box may have several holders. It still omits required permissions and error/reversibility details.

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?

Three front-loaded sentences, each conveying a distinct point (effect, use case/audit, multi-holder). Slightly dense phrasing ('a person of the account') but no filler.

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?

No output schema and only two fully documented parameters, and the description covers the mutation's side effects (recorded, visible to holders). The main gap is absence of permission/authorization requirements for access-granting, which matters for a security-relevant mutation.

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 parameters are richly documented (person = sign-in address, address = mailbox with example and pointer to list_mailboxes). The description adds no parameter detail beyond the schema, so baseline 3 is appropriate.

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 and resource (puts a person on a mailbox) and explains the mechanism: it is 'what lets them read it.' That makes the effect clear, and the input schema separates the mailbox address from queue addresses. It doesn't name sibling tools like add_mailbox_alias or remove_mailbox_holder in the description itself.

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?

Gives one concrete use case (reclaiming correspondence of someone who has left) which implies when to use it, but offers no explicit when-not guidance and no named alternatives. The agent has to infer that remove_mailbox_holder is the inverse.

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