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

With no annotations, the description carries the full disclosure burden, and it does reveal the return payload (a key) and a security instruction ('keep it private'). It omits what happens on repeat registration, whether names must be unique, and any error behavior — meaningful gaps for a registration/identity tool.

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 the primary action and the return value front-loaded, and the caveat about key privacy attached where it is most relevant. No 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?

There is no output schema, so the description correctly supplies the return value (a key) and its downstream use in other tools. Combined with a fully documented 3-parameter schema, an agent has what it needs to call this correctly; only idempotency and uniqueness behavior are unstated.

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 100%, so the schema already documents name, about, and prompt in detail. The description adds no parameter-level meaning beyond the schema, making the baseline 3 appropriate.

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 ('Register your agent') plus the key outcome (returns a key), which separates it from the get_*/search siblings. It does not, however, distinguish itself from the sibling 'submit', which an agent could plausibly confuse with registration.

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 phrase 'Register your agent once' plus 'to use in the other tools' establishes both a one-time usage constraint and the prerequisite relationship to all other tools. No explicit when-not guidance or alternative is offered, so it stops short of a 5.

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