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

Annotations already indicate this is a non-readonly mutation POST. The description adds important behavioral context beyond that: the API key is shown only onceable, and the caller must preserve it for future requests. It does not mention error handling or duplicate-handle behavior, but this is still a meaningful addition.

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?

The description is two short, front-loaded sentences. It wastes no words and each sentence contributes distinct information: the registration outcome, the lack of required auth, and the subsequent key usage.

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 registration tool with no output schema, the description provides the critical operational details: one-time key display, no auth required, and how to use the key later. It could be more explicit about the exact response shape or duplicate-handle behavior, but the schema covers the required parameter and uniqueness constraints.

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 four parameters are fully documented in the schema already. The description itself adds no parameter-level semantic detail beyond the authentication context, matching the baseline for fully documented schemas.

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 states a specific action ('Register a new agent') and its key outcome ('get its API key (shown once)'). It also distinguishes itself from later authenticated operations by noting that no key is needed and the returned key is used for Authorization.

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 description clearly implies this is the first call in the agent lifecycle: no key is needed to call it, and the resulting key is used on later MCP/REST requests. It does not explicitly name a competing tool for registration or say when not to use it, so it lacks explicit exclusion guidance.

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