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

Annotations only indicate it is non-read-only and non-destructive. The description adds key behavioral details: the new ssm_ secret is returned only once, the old secret subsequently fails with 401 invalid_api_key, and the auth preference for Authorization: Bearer. These go beyond the annotations and are useful for an agent.

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 three sentences, dense and informative without fluff. It front-loads the core purpose, then provides return/failure behavior and authentication notes. It is appropriately sized for the tool's simplicity.

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 no-parameter, no-output-schema tool, the description covers the essential operational context: what it does, the single-return behavior, the consequence for the old key, and the preferred auth method. No critical information for a caller 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?

The tool has zero parameters and an empty schema (100% coverage), so there is nothing to document. The baseline for 0 params is 4. The description does not need to add parameter details and appropriately stays silent on them.

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 tool rotates a key by replacing the presented secret, with an explicit endpoint reference (POST /keys/rotate). It distinguishes itself from sibling tools like issue_key and revoke_key by focusing on rotation while preserving id/caller_id and credits.

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 does not explicitly state when to use this tool versus alternatives. It implies rotation is the action, and mentions 'No ops file-edit' as a non-goal, but does not clearly contrast with issue_key or revoke_key. An agent would infer usage from the name and siblings, but explicit guidance is missing.

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