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

The description adds critical behavioral context beyond the annotations: the secret is returned only once and must be saved immediately. Annotations already declare this is a non-read-only, non-idempotent, non-destructive operation, so the description's warning about one-time secret exposure is the key additional disclosure. It does not mention rate limits or duplicate-name behavior, but the one-time-secret detail is materially useful.

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 two short sentences with zero wasted words. The core action is front-loaded, and the critical operational warning follows immediately.

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 one-parameter creation tool with clear annotations and no output schema, the description covers the essential behavior an agent needs: it creates a key and returns the secret only once, making the immediate-save requirement explicit. Nothing critical is missing for correct invocation.

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 100%, and the single parameter 'name' is fully documented in the schema with an example. The description adds no further parameter semantics beyond what the schema already provides, so the baseline score of 3 is appropriate.

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: 'Create a new API key.' It clearly distinguishes this action from sibling tools such as key_list and key_delete, which respectively list and delete API keys. An agent can identify the tool's purpose without opening the schema.

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?

The description explains how to handle the result ('save it immediately') but gives no guidance on when to use this tool versus alternatives like key_list or credential_save. It does not state conditions, prerequisites, or exclusions, leaving usage context to inference from the tool name alone.

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