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

Annotations only declare readOnlyHint=false and idempotentHint=false, so the description adds real value by disclosing that the key is free, must be retained, and is displayed only once – a non-recoverable secret. It does not say what happens if it is called repeatedly (relevant given idempotentHint=false), which keeps it from a 5.

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 compact sentences with zero filler. The action is front-loaded, followed immediately by the retention warning, which is the highest-value fact for the caller.

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 and no parameters, the description carries the burden of explaining the return value, and "it is shown once" does that adequately plus flags the auth prerequisite. The remaining gap is the absence of guidance on repeated invocation creating additional non-idempotent keys.

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 takes zero parameters and schema coverage is effectively 100%, so there is no parameter meaning to add; the baseline for a param-free tool applies. Nothing in the description misleads about inputs.

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?

"Mint a free agentclash API key" gives a specific verb (mint) and resource (API key) with the scope qualifier (free). No sibling tool (get_image, get_result, guess, start_practice) overlaps with key provisioning, so an agent can select this unambiguously from the name plus description alone.

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?

"every other tool needs it" establishes the prerequisite ordering – an agent knows to call this before attempting any other tool. It stops short of explicit when-not guidance (e.g. whether to re-mint if a key already exists), so it falls below a full 5.

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