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

With no annotations, the description carries the full burden: the verb "Lists" weakly implies a read-only operation, and it gestures at what the response contains (address, signature block, aliases). But it never states that it is read-only, whether it requires permissions, or how results are ordered or bounded.

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 sentences, but the second is oracular shorthand that forces the reader to decode meaning rather than commit space to useful detail. The leading clause is correctly front-loaded.

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, so the description should explain the return shape; it does partially (address, closing block, mailbox aliases), but through obscure phrasing that leaves the actual field contents uncertain.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 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 opening clause "Lists the inbound addresses of the account" gives a specific verb and resource, but the rest of the sentence is cryptic ("the block that closes what is written from it" presumably means signature, "the other names that deliver into it" presumably means aliases). It never differentiates itself from sibling list_mailboxes, which an agent could easily mistake for the same data.

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?

"Sending from any of these is what brings the answer back into the mailbox" hints at a purpose but gives no explicit when-to-use, no prerequisites, and no named alternative such as list_mailboxes. The agent must infer the selection condition.

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