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

Annotations already declare readOnly, idempotent, and non-destructive, so safety is mostly covered. The description adds two pieces of genuinely useful context not in the annotations: the result never includes secret values, and the call is 'Free' (presumably no credit cost). It omits ordering, pagination, and any access/permission caveats.

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 tight sentences front-load the returned fields before the crucial 'never the values' constraint. The one-word fragment 'Free.' is efficient but slightly cryptic out of context, which keeps it from a 5.

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?

With no parameters and no output schema, the description carries the burden of explaining the return shape, and it does so field by field for a list-style tool. The security-relevant exclusion of values and the cost note cover what an agent needs before invoking it.

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 takes zero parameters, so there is nothing for the schema to document and no semantic gap to fill. The description correctly describes only the output, which is the right use of space for a parameterless tool.

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?

It states precisely what the tool returns: secret names plus username, URL, note, readers, and last-read timestamps. The resource (vault secrets) and the shape of the result are clear, though the verb is implicit rather than stated as 'list'. It does not explicitly contrast with vault_get or vault_search, but 'never the values' implicitly separates it from retrieval tools.

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?

There is no explicit when-to-use statement or named alternative; the agent must infer from 'Never the values' that vault_get is the tool for actual secret values. That inference is reasonable but is implied rather than stated, and nothing covers when-not to call it.

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