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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered structurally. The description adds genuine value beyond that: it is scoped to the credential the server itself uses, lists the exact data returned, and identifies the diagnostic use case (permission failures). It stops short of saying whether the key's secret is ever exposed or whether the call itself requires auth.

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?

Two sentences, front-loaded with the return payload, then the use case. Concrete scope examples communicate the kind of data better than an abstract phrase would, and nothing is padded.

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?

With no parameters and no output schema, the description carries the full burden of explaining the response, and it does name the fields an agent will receive. Minor gaps remain (response shape, whether expiry can be null, whether the secret is masked), but an agent has enough to call and interpret it.

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?

Zero parameters, so there is nothing for the description to disambiguate; the baseline for a no-argument tool applies. The description correctly signals the call takes no inputs by describing only the returned data.

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 resource (the API key this server uses) and enumerates exactly what is returned: granted scopes with concrete examples (list.view, contact.create, message.edit, report.view) plus creation/expiry time. The name 'get_account' is ambiguous, but the description resolves it and clearly distinguishes this credential-inspection tool from the sibling CRUD tools on lists, contacts and messages.

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?

"Use it to see why a request is refused" gives an explicit triggering scenario, which is more than most definitions offer. It does not name an alternative or state when not to call it, but given the sibling set is all resource-level CRUD, no obvious alternative exists to route away from.

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