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

Adds real behavior beyond the readOnlyHint/destructiveHint annotations: it discloses the return shape, that the key itself is never returned, that valid is null when not checked, and that an owner token is required. The only gap is that it doesn't say what access values look like or whether repeated calls are rate limited.

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?

Very short and front-loaded: the core purpose, the return shape, and the safety caveat come first. The telegraphic phrasing ('Whether a key is saved...') is slightly clipped but nothing is wasted.

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?

No output schema exists, so describing the { saved, valid, access } shape and the null-valid case is necessary and well done. However, for a two-required-parameter tool with zero schema descriptions, an agent still cannot tell what app vs name should contain, which is the main completeness gap.

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 coverage is 0% — neither 'app' nor 'name' is described anywhere. The description only says 'a key', giving no hint that 'app' scopes the vault namespace and 'name' identifies the key, so it fails to compensate for the schema gap on both required parameters.

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+resource: checks whether a key is saved in the vault, and names the returned fields ({ saved, valid, access }). That distinguishes it from sibling tools like request_secret, though it never names an alternative explicitly.

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?

Usage is only implied — an agent must infer that this is a pre-check before calling request_secret or owner_command. The prerequisite 'Needs an owner token' is stated, which is genuine usage context, but there is no when-to-use/when-not guidance and no named alternative.

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