Verify credentials and upstream reachability

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

Annotations already mark the tool as read-only and idempotent, and the description adds substantial behavioral detail beyond that: it never returns the credential, it distinguishes 'no credential' from 'credential rejected' from an api.tempo.io-side problem, and it reports round-trip time. This is exactly the kind of context an agent needs.

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?

Three sentences carry exactly the necessary information: what it does, what it reports, and when to call it. It is front-loaded with the core mechanism and contains no filler or repetition beyond the useful read-only credential-safety note.

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 parameterless diagnostic tool, the description covers the operational behavior, security-relevant credential handling, output elements, and invocation conditions. The annotations cover safety and idempotency, so nothing needed for correct use 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 coverage, there are no parameter semantics for the description to clarify. The description appropriately concentrates on behavior instead, which is the right choice for a parameterless tool.

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 diagnostic action: resolve the credential, make one authenticated request to api.tempo.io, and report which hop failed. This clearly distinguishes tempo_healthcheck from the many sibling data tools by describing a verification/diagnostic purpose rather than a CRUD or query operation.

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 final sentence explicitly instructs when to invoke it: 'Call this when a real tool fails and you want to know which hop broke.' This gives an agent a direct decision rule for choosing this tool over ordinary Tempo operations.

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