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

Annotations already declare readOnlyHint=false, so the agent knows this is a mutation; the description adds real value beyond them by specifying the Bearer auth requirement, the read-only scope of the resulting key, and the critical one-time-only return of the key value. It does not mention expiry or revocation, which would complete the picture.

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 compact sentences, front-loaded with purpose, then auth, then the one-time return caveat. Nothing repeats the title or wastes tokens.

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?

With no output schema, the description correctly volunteers that the key value is returned once, which is the most important return-value fact. The remaining gap is the unexplained 'name' parameter, the only input the caller must supply.

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 single parameter 'name' has 0% schema description coverage and the description never mentions it at all — it does not say whether the name labels the auditor, the key, or is required. With a low-coverage schema the description must compensate, and here it does not.

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 ('issue a read-only sub-key'), names the scope ('on your own slice'), the recipient, and the exact capability set. An agent can distinguish it from list_receipts/get_statement/write_receipt without opening any schema.

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?

Clear context for when to use it — provisioning an auditor with a restricted key — and the permission ceiling is spelled out. No explicit exclusion such as an alternative provisioning path, but the intended usage is unambiguous.

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