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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds meaningful behavioral context by revealing that this call surfaces a plaintext password plus IMAP/SMTP configuration — sensitive output an agent should know about — but says nothing about permission requirements or whether credentials are always present.

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?

A single short sentence with no filler, front-loading the returned data. It is efficient, though slightly under-specified rather than optimally concise for a credentials-returning tool.

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 trivial one-parameter read tool with full annotation coverage this is close to adequate, and it names the three outputs. However, with no output schema present, the description could state the actual shape of the return (host/port/SSL per protocol) and should flag that credentials are exposed; those gaps keep it at minimum-viable.

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?

With one parameter and 100% schema description coverage ('Mailbox address, e.g. sales@yourdomain.com'), the schema already fully documents the input. The phrase 'for one of your hosted mailboxes' reinforces that email selects the mailbox but adds no syntax or format 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 description names the concrete payload returned — password, IMAP and SMTP settings — for a hosted mailbox, which is far more specific than the tool name alone. It lacks an explicit verb ('retrieve'/'get') and does not distinguish itself from siblings like get_mailbox or connect_imap_mailbox, so it stops 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?

There is no statement of when to call this versus get_mailbox, connect_imap_mailbox, or test_mailbox, all of which live in the same mailbox area. The agent must infer usage from the noun phrase alone, and no prerequisites or exclusions are given.

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