Update mailbox

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

Annotations only state the safety profile (not read-only, not idempotent, not destructive, open-world); the description goes well beyond that by disclosing the verification prerequisite for set_default, that email changes stay pending until verified, the one-way semantics of set_default/cancel_email_change, the mutual exclusivity of email and cancel_email_change, and that no-op calls are rejected locally without hitting SimpleLogin.

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?

Purpose is front-loaded in a short first sentence, and the constraint detail follows. The second sentence is a dense run-on stacking several clauses, but each clause carries distinct operational information, so little is wasted.

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 need not explain return values, and with annotations covering the safety profile plus a thorough account of preconditions, side effects, and parameter interactions, an agent has everything required to invoke this tool correctly.

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%, so the baseline is 3, but the description adds semantics the schema does not convey: that set_default and cancel_email_change only accept true (constraint exists in schema but the reason is only in the description), and that email and cancel_email_change are mutually exclusive — an interaction the schema cannot express.

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 opens with a specific verb+resource ('Update a mailbox') and enumerates the three distinct mutations available (set_default, email change, cancel_email_change), which clearly separates it from mailbox_create/mailbox_delete. It does not explicitly name a sibling, so it falls short of a 5.

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?

It gives concrete operative conditions: at least one change is required, set_default requires a verified mailbox, and a no-op call is rejected before contacting SimpleLogin. That tells an agent when the call will succeed or fail, though it never routes the agent to an alternative sibling tool for related tasks.

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