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

Annotations already declare destructiveHint=true and idempotentHint=false, and the description adds real value beyond that: the concrete consequence ('Old key stops working'), the new key's required format (32-byte lowercase hex), and a security constraint about secrets in model context. It does not cover authorization requirements or confirmation behavior, but the added context is substantial.

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 short sentences, each earning its place: the operation, the consequence, and the safety constraint. Front-loaded with the action and free of 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 destructive, non-idempotent key-rotation tool with no output schema and undocumented parameters, the description covers the effect and format but omits what the 'key' input is, any auth/permission requirements, and the expected response. Adequate but with visible gaps.

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 0% for both params, so the description must compensate. It does explain the format of new_key (32-byte lowercase hex) and hints the key is a secret, but it never clarifies what the 'key' parameter is (the existing participant key). Partial compensation for a two-parameter mutation.

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 gives a specific verb and resource ('Replace your participant key'), plus the exact nature of the replacement (client-generated random 32-byte lowercase hex). It is distinguishable from revoke_key by framing the operation as a replacement rather than a removal, though it never names the sibling explicitly.

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?

There is no statement of when to use this versus revoke_key or the other key-management siblings. The line 'Do not put secrets in model context' is an operational caution, not usage routing, leaving the agent to infer the trigger conditions for rotation.

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