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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered; the description adds the non-obvious guarantee that secret material is never returned, which matters for a credential-inspection tool. "Takes no arguments and changes nothing" partly restates the annotations, so the net new information is narrower than it first appears.

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 what is returned, then when to call it. Every clause carries either scope, return content, or a usage trigger; 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?

For a zero-argument, read-only diagnostic with no output schema, the description names the three returned items and states the security constraint, which is sufficient to call it correctly. It does not describe the shape of the returned scopes or tenant boundary, a minor gap given no output schema exists to cover 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?

With zero parameters, the baseline is 4, and the description correctly confirms "it takes no arguments," matching the empty schema with additionalProperties=false. Nothing further is needed on this dimension.

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 ("Show") and a precisely enumerated resource: the current API-key type, granted scopes, and browser tenant boundary. The scope statement ("without exposing secret material") and the note that it takes no arguments make it immediately distinguishable from the data_* siblings, all of which act on requests, batches, or results.

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?

Gives two explicit triggers: "Call it first when unsure which tools this key unlocks" and "after a permission error to check the granted scopes." These are concrete, actionable conditions rather than generic advice, and no alternative tool could be substituted for this diagnostic check.

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