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

Beyond the annotations, the description discloses critical behavioral details: the new secret is returned only once and the old secret will fail with 401 after rotation. This adds real operational context. The description does not contradict the provided annotations.

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 tightly packed sentences with no filler. The core behavior is front-loaded, and every sentence adds a distinct, useful fact: endpoint, identity/credit preservation, one-time return, old-key invalidation, auth preference, and the no-ops-file caveat.

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 mutation with no output schema, the description covers the essential operational contract: how to authenticate, what changes, what is returned once, and what happens to the old key. Minor gaps remain around idempotency or permission requirements, but nothing critical for a competent agent is missing.

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 zero parameters, so the baseline is 4 and the description does not need to explain parameter meaning. It appropriately relies on the auth context rather than inventing parameter documentation.

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 action ('Replace the presented secret'), names the endpoint, and clarifies the identity/credit impact. This clearly differentiates it from siblings like issue_key and revoke_key without needing to open their schemas.

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?

It gives useful invocation guidance: prefer Bearer auth, X-API-Key is only an alias, and no ops file-edit. However, it does not explicitly explain when to choose rotate_key over issue_key or revoke_key, nor does it state any exclusions or prerequisites.

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