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

Annotations already declare the tool as read-only, idempotent, non-destructive, and not open-world. The description adds value by specifying the returned content (status, environment, version), which is useful context beyond the structured safety hints. However, it does not disclose any further behavioral traits such as authentication requirements or rate limits.

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 that efficiently communicates the tool's purpose without any wasted words. It is appropriately sized for such a simple probe.

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 tool's simplicity (0 parameters, no output schema) and the annotations covering its safety profile, the description provides enough context by stating what it returns. It could be slightly more complete by mentioning that it takes no arguments or by noting typical usage, but it is largely sufficient.

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 accepts zero parameters, and the schema description coverage is 100% (vacuously). Per the rubric, a zero-parameter tool receives a baseline of 4, as there are no parameter semantics to clarify.

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 names a specific verb ('Returns') and resource ('upstream API status, environment, and version'), making the tool's function immediately clear. No sibling tool performs a similar health/status check, so it is easily distinguishable from the rest of the toolset.

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 offers no explicit guidance on when to use this tool versus alternatives, nor does it state any prerequisites or exclusions. While the name 'healthz' implies a health-check use case, the description itself provides no such direction.

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