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

Goes well beyond the sparse annotations by disclosing the key behavioral consequences: old secret returns 401 invalid_api_key, new secret is shown only once, and no ops file-edit occurs. This is exactly the kind of side-effect clarity an agent needs.

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?

Four short, information-dense sentences. The main action is front-loaded, and every sentence adds distinct value—behavior, return behavior, auth preference, and operational caveat—with 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-parameter tool with no output schema and minimal annotations, the description is remarkably complete. It tells the agent what happens, what the response contains, how the old credential behaves, and how to authenticate.

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 are no parameters, so the baseline is 4. The description still adds useful context about what is preserved (id/caller_id and credits), which helps an agent reason about the operation's semantics even without inputs.

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 action ('Replace the presented secret') with the resource and endpoint (POST /keys/rotate). It is clearly differentiated from siblings like issue_key, revoke_key, and verify_key, and the title's odd suffix does not undermine the description.

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 clear operational context: same id/caller_id and credits are preserved, and the new secret is returned only once. It also gives concrete auth guidance (prefer Bearer; X-API-Key is alias only), though it does not explicitly name when-not-to-use alternatives.

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