yubikey-fido-credentials

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

No annotations are provided, so the description must disclose behavioral traits. It correctly indicates that a PIN is required, but does not explain whether the operation is read-only or has side effects. Since it lists credentials, it is likely read-only, but this is not confirmed.

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 sentence plus a short requirement note, making it extremely concise and front-loaded. Every word contributes to understanding.

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?

There is no output schema, so the description should indicate what the tool returns (e.g., list of credentials with metadata). It omits this, making it less complete for an agent to understand the full input-output behavior.

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 input schema has 100% description coverage. The tool description adds value by stating the PIN is required and that the serial parameter can be omitted if only one key is connected, which is not fully captured in the schema descriptions.

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 lists FIDO2 resident credentials (passkeys) stored on a YubiKey, using specific verb 'List' and resource 'YubiKey'. It distinguishes from sibling tools that handle other YubiKey functions (fingerprints, info, PIV, etc.).

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 mentions 'Requires PIN' but does not explicitly specify when to use this tool versus alternatives like yubikey-fido-fingerprints or yubikey-piv-keys-info. Usage context is implied but not detailed.

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