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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=true, so safety and repeatability are covered by structured data. The description adds one genuinely new trait — that the call has no cost — but says nothing about latency, auth requirements, or what distinguishes a healthy from a degraded result.

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 short sentences, zero filler, with the core function front-loaded and the cost note as a secondary qualifier. Nothing is wasted and nothing important is buried.

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, no nested objects, and rich annotations, the only remaining gap is return shape: there is no output schema and the description does not say whether the result is a boolean, a status string, or a version payload. Minor, but it means an agent cannot predict the response format.

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 no parameter semantics for the description to explain. Baseline for a zero-parameter tool applies, and the description correctly avoids inventing parameter commentary.

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 and resource: 'Check that the service is up.' That is unambiguously a liveness/health probe and cannot be confused with the data-retrieval siblings get-alerts and get-forecast. It stops short of naming the service or endpoint being probed, but the intent is clear.

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?

'Costs nothing' hints that it can be called freely, which weakly implies a pre-flight or connectivity-validation use case. However, it never says when to call it versus the siblings, nor whether it validates auth or downstream dependencies versus simple process liveness. Usage is implied rather than stated.

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