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

Annotations already declare destructiveHint=true and idempotentHint=true; the description adds genuinely new context — billing impact and that the key is never returned. However, it never explains the destructive path: overwriting an existing key or using the `clear` flag to remove one, which is exactly what the destructive hint warns about.

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?

Two short sentences, front-loaded with the action and then the consequence. Zero filler, nothing redundant with the title.

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, zero-schema-coverage mutation, the description covers storage, billing, and secrecy but omits key replacement/removal behavior and any permission or number-validity prerequisites. An agent could call it correctly in the happy path but would be guessing about `clear`.

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%, so the description must carry the load. It loosely identifies the key and the target number, but leaves the boolean `clear` parameter completely unexplained — the most semantically ambiguous and destructive parameter of the three.

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 verb and resource ("Stores an OpenAI key on this number's receptionist") and immediately explains the effect on calls and WhatsApp replies. No sibling tool sets an OpenAI key, so the action is unambiguous against upsert_receptionist or enable_whatsapp_ai.

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 billing consequence ("Widely does not charge tokens") implies why an agent would use it, but there is no explicit when-to-use, prerequisite, or when-not guidance. Nothing tells the agent how this relates to sibling configuration tools such as upsert_receptionist or update_whatsapp_ai.

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