Verify credentials and upstream reachability

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

Annotations already mark this read-only and idempotent, but the description adds valuable behavioral context: it never returns the credential itself, resolves the credential through the same path as real tools, and performs exactly one authenticated request. There is no contradiction with the annotations.

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: purpose first, then output details, then the read-only caveat, then the trigger condition. Every sentence earns its place and there is no filler.

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?

Even without an output schema, the description enumerates the returned diagnostic fields (credential source, acceptance, round-trip time, failure hint) and the failure classes it distinguishes. For a zero-parameter healthcheck tool, this is sufficient for an agent to understand and interpret the result.

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 the description carries no burden to explain parameter meaning. Per the baseline for zero-parameter tools, this is appropriately handled; the description instead clarifies what the tool reports, which is what matters for invocation.

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 precise diagnostic purpose: resolve credentials the way real tools do, make one authenticated request, and report which hop broke. This clearly distinguishes it from sibling data and mutation tools, so an agent can select it for healthcheck rather than for normal CRUD operations.

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 tells the agent when to call it: 'Call this when a real tool fails and you want to know which hop broke.' It provides clear context for use, though it does not explicitly say when not to use it or name alternatives.

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