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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false. The description adds one genuinely useful behavioral fact beyond them: the plaintext is returned only once and must be stored, meaning it cannot be re-retrieved later. It omits what the key grants, whether repeated calls with the same name produce duplicates, and whether creation is reversible.

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 with no filler, and the most operationally important warning is front-loaded. It is efficient, though so terse that the core action is left implicit.

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 credential-minting mutation with a nested body, no output schema and zero parameter documentation, the description covers the single most critical behavior (one-time plaintext) but leaves the action itself, the name parameter, and the key's scope unaddressed.

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?

There is one parameter (body.name) at 0% schema description coverage, and the description says nothing about it — no naming constraints, uniqueness, or effect of the name. With low coverage the description should compensate, and it 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?

The description states a key fact about the outcome (plaintext returned once) but never says the tool creates/generates an API key, what kind of key, or at what scope. The verb must be inferred from the name key_create, and there is no differentiation from sibling key_revoke or keys.

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?

No when-to-use or when-not-to-use guidance is offered: nothing about which account/scope the key belongs to, prerequisites, or why an agent would choose key_create over key_revoke or keys. Only a post-call storage warning is given.

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