fastmail_list_emails

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

With no annotations provided, the description carries the full burden of behavioral disclosure, and it only says 'List' and 'Supports filtering'. It does not state whether the operation is read-only, how results are ordered or paginated, or what data is returned about each message.

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 terse sentences carry the core purpose and available filters with no redundant words. The primary scope is 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?

For a simple list operation with no required parameters and full schema coverage, the description is adequate but not rich. There is no output schema, so the description should have at least hinted at return shape (summary vs full content) or ordering to make the tool fully self-contained.

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?

Schema coverage is 100%, so the baseline is 3. The description loosely echoes the folder, unread, and search parameters but adds no extra semantics such as what search targets (subject, body, etc.) or how limit interacts with pagination.

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 uses a specific verb (List) and resource (emails), and scopes it to inbox or other folders. This distinguishes it from sibling tools like fastmail_get_email (single message) and fastmail_list_masked_emails (masked addresses).

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 implies this is the tool for retrieving email messages with optional filters, but it never explicitly contrasts it with alternatives or states when-not-to-use. An agent can infer use from 'List emails' but receives no direct routing guidance.

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