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

Goes well beyond the annotations (destructiveHint=true, idempotentHint=true) by disclosing the 10-minute grace window, the fact that the old key stops working after it, that the new key is shown only once, and that the call is never replayed. These are exactly the operational details an agent needs to avoid losing credentials.

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 tight sentences that front-load the action before the caveats, and each carries a distinct operational fact. The second sentence ('Your other clients keep their keys') mildly restates the scope already given in sentence one, but it usefully removes ambiguity about blast radius.

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 single-parameter, destructive mutation with an output schema present, the description covers the key behavioral risks (grace period, one-time display, idempotency). It omits permission/auth prerequisites required to rotate a key, which would be the last piece an agent needs.

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?

Schema description coverage is 100%, so the idempotency_key semantics (8-128 chars, reuse only for exact retries) are already documented in the schema. The description reinforces the retry purpose but adds no syntax or format detail beyond that, so the baseline 3 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?

States a specific verb ('Issue') and resource ('a new API key') plus an explicit scope constraint ('for this client only'). The description also distinguishes the affected scope from unaffected ones ('Your other clients keep their keys'), so an agent knows exactly what is and is not rotated.

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?

It gives clear invocation context: the 10-minute overlap exists so a retry after a lost response can recover, and the idempotency key is for retrying this exact call. It does not, however, state when not to rotate or name any alternative operation, so it falls short of full when/when-not guidance.

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