list-accounts

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

The description discloses the return value (account names and count) and implies read-only behavior. No annotations exist, so the description carries the full burden; it is sufficient but could mention safety or side effects explicitly.

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 description is extremely concise, consisting of two clear sentences. The first sentence front-loads the purpose and return, the second provides when-not-to-use. No wasted words.

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 parameterless tool with an output schema, the description is fully complete. It covers purpose, usage guidelines, and return value, leaving no gaps.

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 has no parameters, so schema coverage is 100%. The description adds value by stating what is returned (account names and count), which complements the absent parameter details.

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 clearly states the tool's purpose: discovering configured Mail accounts and returning account names with a count. It explicitly distinguishes from sibling tools like list-mailboxes and 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 description provides explicit 'Use when' and 'Do not use when' guidance, including specific alternative tools (list-mailboxes, list-messages/search-messages) for different scenarios.

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