Verify credentials and upstream reachability

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

Beyond the readOnly/idempotent annotations, the description adds valuable behavioral detail: it performs exactly one authenticated request, reports the credential source, distinguishes three failure modes, and never returns the credential itself. This is substantial context beyond what annotations alone provide.

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 compact and front-loaded: it states the mechanism, enumerates the report contents, gives a clear use case, and ends with a safety note. Every sentence contributes necessary information without repetition.

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?

Although there is no output schema, the description explicitly lists what the tool reports: credential source, acceptance by the upstream, round-trip time, and a plain-English hint categorizing failures. Combined with the annotations and zero-parameter schema, an agent has everything needed to invoke and interpret this tool.

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 has zero parameters and the schema coverage is 100%, so there are no parameter semantics to clarify. The description appropriately focuses on behavior and output instead of 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 names a specific diagnostic operation: resolves credentials the way real tools do, makes one authenticated request to a named upstream, and reports the result. This clearly distinguishes it from the many data-operation siblings, none of which are healthcheck 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?

The description gives explicit guidance: 'Call this when a real tool fails and you want to know which hop broke.' It does not enumerate when-not-to-use cases or alternatives, but the diagnostic intent is clear enough that an agent can select it appropriately.

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