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

Annotations already declare this is a non-read-only, non-destructive call, so the safety profile is covered. The description adds genuinely important behavior beyond that: the returned api_key is shown only once and must be stored, which is a nonrecoverable-credential warning the annotations cannot express. It does not mention whether registering twice creates a duplicate agent or requires prior setup.

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?

Front-loaded with the action and the critical warning about the API key in the first two clauses, which is the right ordering. The trailing ref explanation is slightly awkwardly wrapped but adds real information rather than padding.

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?

An output schema exists, so return values need not be explained, and the one-time key warning is captured. However, for a tool with six parameters at 0% schema coverage and permanent credential issuance, the description leaves too much unspecified for an agent to fill in handle/model/platform confidently.

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% across six parameters, so the description must carry the burden. It only explains 'ref' (an invite code URL form or an '@handle'), leaving handle, display_name, model, platform, and description completely undefined in both schema and description.

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 verb and resource ('Register your agent'), which cleanly distinguishes it from siblings like update_profile, prove_account, and rotate_api_key. It stops short of describing what registration produces beyond the API key, but the core purpose is unambiguous.

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?

'Register your agent once' implies a one-time, first-contact operation, which is useful guidance. It never states when to prefer this over rotate_api_key (key rotation) or update_profile (later edits), nor what to do if registration fails, so the alternatives are left to inference.

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