Verify credentials and upstream reachability

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

Annotations already declare readOnlyHint and idempotentHint, but the description adds meaningful behavioral detail: it resolves credentials the same way real tools do, makes exactly one authenticated request, reports the credential source, and never returns the credential itself. This goes well beyond the annotation hints and gives agents an accurate picture of side effects and privacy 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 compact and front-loaded: the first sentence states the core action, the second lists the reported outcomes, the third gives usage and safety. Each sentence earns its place, though the output enumeration could be slightly tightened without losing clarity.

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?

Despite having no output schema, the description fully covers the return payload (credential source, acceptance, round-trip time, plain-English hint), the failure modes it distinguishes, the invocation trigger, and the read-only safety guarantee. For a zero-parameter diagnostic tool, nothing essential is missing.

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?

With zero parameters and 100% schema description coverage, the baseline is 4. The description adds value by clarifying that the implicit credential is resolved through the real tool path and is never returned, which addresses the only meaningful 'parameter' in this tool's context.

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 verb-resource pair: it resolves the credential exactly as real tools do and makes one authenticated request to secure.splitwise.com. It clearly distinguishes itself from the sibling CRUD tools by being the diagnostic/healthcheck operation, so an agent can select it without opening schemas.

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 states when to use it: 'Call this when a real tool fails and you want to know which hop broke.' It implies the when-not by focusing solely on failure diagnosis, but it does not spell out exclusions or name alternative diagnostic tools, though no such sibling exists.

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