list_address_books

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

No annotations are provided, so the description carries the full behavioral disclosure burden. It correctly implies a read-only listing operation, but does not mention any limitations, return format details, or account-specific nuances. Since it is a simple list with no side effects, the minimal description is adequate but not rich.

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 a single, clear sentence that wastes no words. It includes the essential information (what is listed and the scope) without redundancy.

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?

The tool has no output schema and no annotations, so the description is the only source for understanding the return value. While 'List all address books' implies a list of address books, it does not specify whether the response includes contact counts, ordering, or other metadata. For a simple tool, this is a minor gap but could be more complete.

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, and schema_description_coverage is 100% by default. The description adds no parameter-specific semantics because none exist, and it implicitly communicates that no filtering is available. Baseline for zero parameters is 4.

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 verb 'List' and the resource 'address books (contact groups)' in the Fastmail account, distinguishing it from sibling tools like list_calendars and list_mailboxes. The parenthetical clarification disambiguates the term 'address books' from other possible meanings.

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 usage when one needs all address books, but it does not explicitly state when to use this tool over alternatives like search_contacts or get_contact. No exclusions or alternative guidance are provided, which is acceptable for such a straightforward list operation.

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