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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: it returns METADATA fields only and explicitly excludes the underlying card number and PII. It does not describe pagination behavior or rate limits, but that is a minor gap.

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 tightly written sentences front-load the key scope ('as METADATA') and returned fields, followed by a concise API endpoint reference. Every clause earns its place and there is no 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?

For a read-only list tool with 100% schema coverage and no output schema, the description usefully names returned metadata fields and the PII exclusion. It is nearly complete, though it could briefly clarify pagination or ordering behavior rather than relying entirely on the start parameter's schema description.

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 100%, and the schema already documents all five parameters including the fingerprint/duplicate-finding semantics. The description mentions returned fields rather than parameter behavior, so it adds little meaning beyond the schema, making the baseline 3 appropriate.

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?

States a specific verb ('List') and resource ('vault tokens'), and scopes it to METADATA with named returned fields. It is clearly distinguishable from get_token and search_tokens in practice, but it does not explicitly name or differentiate against those siblings.

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 a listing operation but gives no explicit when-to-use guidance, no prerequisites, and no alternatives such as search_tokens or get_token. The PII note is behavioral context, not usage routing.

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