list_users_with_passkey

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

Annotations already disclose readOnly, idempotent, and open-world behavior. The description adds the core filtering behavior—returning only users with a registered passkey/FIDO2—but does not go beyond that with details like output shape, pagination, or permissions. No contradiction with annotations.

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, front-loaded sentence with no filler or redundancy. Every word contributes to the core purpose, which is appropriate for a simple one-parameter list tool.

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?

Given the simple read-only nature and rich annotations, the description is minimally adequate. However, it lacks usage alternatives, parameter semantics, and any note about the returned data shape, which would make it fully self-contained for an agent.

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 description coverage is 0%, and the description does not mention the 'limit' parameter at all. The schema only provides the parameter name, type, and default, leaving the agent to infer its semantics without any compensating explanation.

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 action (list) and the resource (users with passkey/FIDO2 registered). This specific filter distinguishes it from sibling tools like list_users_without_mfa and list_users_with_weak_authentication without needing to inspect schemas.

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 intended use case is implied by the description—call this when you need users who have a passkey/FIDO2 registered. However, there is no explicit when-to-use guidance, no exclusions, and no mention of alternative sibling tools.

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