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

With no annotations, the description carries the full burden and discloses key behavioral impacts: 'After rotation, the current session's key becomes invalid' and 'The new key must be reconfigured.' This warns about destructive consequences and post-conditions, which is valuable beyond the basic action.

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?

Three concise sentences, front-loaded with the primary action and followed by usage context and a warning. No unnecessary words, every sentence earns its place.

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-parameter tool with no output schema or annotations, the description covers purpose, when to use, and important behavioral caveats. It could explicitly mention the return value (the new key), but the instruction 'The new key must be reconfigured' implies it is delivered in the response, making this nearly complete.

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 the schema is automatically 100% covered. Per the rubric, 0 params yields a baseline of 4. The description adds no parameter detail because there are none, which 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 clearly states the action: 'Generate a new API key and invalidate the current one.' It uses a specific verb and resource, and this tool is distinct from all siblings (no other API key rotation tool exists).

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?

Provides explicit usage context: 'Use when the key may have been leaked.' No alternatives are mentioned, but no similar sibling tools exist, so this is sufficient guidance for when to invoke the tool.

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