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

No annotations are provided, so the description carries the full behavioral burden. It discloses that the operation is scoped to the authenticated account and explicitly describes the authentication/session prerequisite. It does not detail output shape or rate limits, but 'list all email addresses' reasonably conveys a read-only collection.

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 core purpose is stated in one clear sentence, and the access requirement is separated as a short note. There is minor redundancy in 'then call this tool again' after mentioning that a session opens this tool, but overall the description is compact.

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 simple zero-parameter list operation, the description covers the return concept, the account scope, and the authentication prerequisite. An explicit output schema would strengthen it, but nothing critical is missing for calling the 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?

The tool has zero parameters, so the description need not document parameter semantics. The phrase 'all email addresses' also clarifies that no filtering is applied. This matches the baseline for a no-parameter tool.

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 states a specific verb and resource: 'List all email addresses associated with the authenticated account.' This clearly distinguishes it from sibling list_* tools like list_phones and list_assets.

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 clear context: a Proof account is required, and the caller must authenticate either via the client or through start_login, then call this tool again. It names start_login as an alternative path, though it does not explicitly address when to prefer this tool over other list_* tools.

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