Is it serving?

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

Annotations already declare readOnlyHint and closed-world; the description adds the crucial non-obvious trait that the data is stale (five-minute sweep, not a probe taken now) and the exact semantics of the returned state and checkedAt. That latency disclosure is exactly the behavioral context annotations cannot carry.

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 sentences, front-loaded with the return semantics then the staleness caveat. Every clause earns its place, with no restating of the name or title.

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, and the description compensates by naming the returned fields and their meaning. For a zero-parameter read tool the description supplies everything needed to call it and interpret the result correctly.

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?

There are zero parameters, so the baseline is 4; the schema is trivially complete and the description correctly describes the return shape (state plus checkedAt) rather than inventing inputs.

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 states a specific resource and its value set: last observed state (healthy/degraded/down/unknown) plus when it was checked. It clearly reads as a status/health read, distinct from siblings like deployment_status or metrics, though it doesn't explicitly name an alternative to distinguish itself.

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?

Explicitly tells the agent this is a five-minute sweep, not a live probe, and instructs to 'compare checkedAt with your deploy' — a concrete when-to-use rule. It stops short of naming sibling alternatives (e.g., metrics or deployment_status), so it lands at 4 rather than 5.

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