Verify credentials and upstream reachability

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

Beyond the readOnlyHint annotation, the description adds important behavioral details: 'never returns the credential itself,' makes exactly one authenticated request, and reports a plain-English hint distinguishing three failure modes. It also explains that credential resolution matches 'the way real tools do,' which is valuable context for understanding the tool's behavior.

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 three sentences of dense, useful information with no filler. It front-loads the mechanism, then the reporting details, then the caveat and usage trigger. Every sentence earns its place.

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 output schema, the description adequately conveys what the agent will learn: credential source, acceptance, round-trip time, and a categorized hint. Combined with the read-only guarantee and usage trigger, an agent has enough to decide when to call and what to expect, despite no structured return schema.

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, so there is nothing for the description to add beyond the empty schema. The baseline for 0-parameter tools is 4, and the description appropriately focuses on outputs and usage rather than parameter details.

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 verb-resource pair: it resolves credentials and makes an authenticated healthcheck request to creditkrama.com, then reports four concrete outputs. This clearly differentiates it from sibling tools that fetch transactions, spending, account summaries, or run SQL, and the phrase 'Call this when a real tool fails' positions it as a diagnostic tool.

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 explicitly says 'Call this when a real tool fails and you want to know which hop broke,' giving a clear when-to-use condition. It does not name alternative tools or explicitly state when not to use it, but the failure-driven context implies it is not for routine operations, so guidance is strong but not fully exhaustive.

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