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

Annotations already cover the safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), so the bar is lower. The description nonetheless adds the single most important behavioral fact: "The key is shown once" — the secret is returned at creation and cannot be retrieved later, which materially changes how the agent must handle the response.

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 short sentences, zero filler, with the core action stated first and the one-time-secret warning immediately after. Nothing could be removed without losing information.

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, the description should say what the create call returns (presumably the secret plus key metadata) and whether the new key inherits the agent's scopes. "Shown once" covers the secret's lifecycle but the returned payload remains unspecified.

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 only 50%: expiresAt is documented as an ISO 8601 date-time, but `label` has no description anywhere. The description adds no meaning to either parameter — it doesn't explain what a label is for or what happens if expiresAt is omitted (no expiry? default?). At 50% coverage the description needed to compensate and does not.

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?

"Creates another API key for this agent" gives a specific verb (creates) and resource (API key), and the word "another" signals this is additive to existing keys, implicitly separating it from apikey_list and apikey_revoke. It does not explicitly name those siblings, so it stops short of a 5.

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?

Usage is only implied: an agent can infer "call this when you need a new credential." There is no explicit statement of when to use this versus apikey_list/apikey_revoke, no prerequisites, and no note on whether key count or permissions are limited.

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