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

Beyond the read-only/idempotent annotations, the description discloses important behavior: the raw key is never returned, `prefix` and `last_four` are shown instead, and when called with an AI assistant sign-in token the response carries a `grant` rather than a `key`. These are meaningful response-shape and access-model details not present in 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 front-loaded with purpose and key usage guidance, and most sentences carry useful context. The opening line repeats the title, which is slightly redundant, but the remaining content is efficient.

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 output schema and no parameters, the description fully carries the burden of explaining the return shape: key metadata vs grant metadata, the masked key fragments, and the first-call use case. Nothing essential for invoking and interpreting the tool 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?

The tool has zero parameters, so there is no parameter semantics to explain. The baseline for a zero-parameter tool applies, and the description does not introduce confusion about inputs.

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 verb and resource: describe the calling key or connection. It distinguishes the two cases (API key vs AI assistant sign-in token) and explains exactly what identity/access information is returned, so an agent can distinguish it from sibling get_* tools.

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 usage context: any valid key may call it, whatever its scopes, and it is the first call to make to check that a key works and see what it can reach. It does not explicitly name when not to use it or compare against a sibling, but the primary use case is unambiguous.

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