mailbox_list_accounts

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

Annotations already declare readOnlyHint=true, so safety is covered, but the description adds real value by enumerating the returned fields (permissions, default, availability) in the absence of any output schema, plus the explicit 'No message content' boundary. The final `server` sentence is ambiguous but does signal connection metadata.

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?

The first sentence is dense and front-loaded with useful field information, but the closing sentence about `server` naming the connection's tool set is cryptic and references a non-existent parameter, weakening an otherwise tight description.

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 usefully documents the return fields an agent needs. The only gap is the unexplained `server` reference, which leaves ambiguity about whether it is an input, output, or internal detail.

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 the baseline is 4. The trailing mention of `server` is confusing since no such parameter exists, but there is no parameter semantics gap to compensate for.

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 (List) and resource (mailboxes/accounts) and enumerates exactly what is returned: address, label, kind, permissions, default flag, availability. The clause 'No message content' cleanly separates it from sibling tools like mailbox_list_messages.

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 mailboxes this credential can use' implies the discovery use case, and 'No message content' hints the agent should go to mailbox_list_messages for content, but no alternative is named and no explicit when/when-not guidance is given.

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