Verify credentials and upstream reachability

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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint. The description adds valuable context: it makes one authenticated request, explains the diagnostic output (credential source, acceptance, RTT), and emphasizes it never returns the credential. This goes beyond annotations, though it could mention rate limits or the exact structure of the hint. With annotations covering safety, a 4 is justified.

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 concise paragraph, front-loading the core purpose and then adding behavioral details. Every sentence contributes value: resolution method, request target, report contents, read-only nature, and usage trigger. No redundancy or fluff.

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?

For a 0-parameter diagnostic tool with annotations covering safety, the description is nearly complete. It covers the request, the response report, and the use case. Minor gaps: it doesn't specify the exact format of the hint or the timeouts/pagination, but given the simplicity and output schema absence, it's adequately complete, not perfect.

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 0 parameters, so the description doesn't need to document any. The baseline for 0 params is 4, and the description appropriately clarifies the tool's behavior without parameter details. It doesn't subtract for missing param info because there is none to describe.

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 clearly states the tool resolves credentials and makes a health-check request to api.getyourguide.com, reporting credential source, acceptance, and RTT. This distinct purpose is well differentiated from sibling tools which all focus on data retrieval (tours, availability, reviews, categories, locations), making it clear this is a diagnostic tool rather than a data 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?

Explicitly states when to use: 'Call this when a real tool fails and you want to know which hop broke.' This gives clear context and a specific trigger condition. It doesn't name alternatives explicitly, but given the sibling tools are all data-retrieval tools, the contrast is implicit and the trigger is unambiguous, earning a 5.

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