Verify credentials and upstream reachability

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

Annotations already cover readOnlyHint, openWorldHint, and idempotentHint, yet the description adds genuinely new behavior: it makes a live network request to whyjuggle.com, exercises the same credential resolution path as real tools, never echoes the credential back, and returns timing plus a plain-English fault classification. Since no output schema exists, this is the only place the return shape and the no-secret guarantee are stated.

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?

Four sentences, each doing distinct work: what it does, what it reports, the safety guarantee, and the trigger. The behavioral payoff ('which hop broke') is front-loaded in the final sentence and nothing is repeated from the annotations.

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 with no output schema, the description supplies everything an agent needs: the side effect (one outbound authenticated request), the returned fields, and the three-way fault distinction it can act on. Annotations cover the safety profile, so no gap remains.

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 takes zero parameters, so there is nothing for the description to disambiguate and the schema carries no semantic burden. Baseline for a 0-param tool applies.

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?

Uses a specific verb chain — resolves the credential, makes one authenticated request to whyjuggle.com, reports source/acceptance/latency — so the agent knows this is a connectivity/auth diagnostic, not a data tool. That purpose is unmistakable against the sibling set of booking, sitter, and messaging 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?

'Call this when a real tool fails and you want to know which hop broke' gives an explicit trigger condition and implicitly positions it as a follow-up rather than a primary action. It stops short of naming a when-not case (e.g. don't call this routinely before every operation) or naming a specific alternative, so it falls just under the top band.

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