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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, but the description adds the critical non-obvious trait that the API key is 'shown once' and therefore must be persisted. It also discloses the proof-of-work prerequisite and the auth header format. It does not cover failure modes (e.g. duplicate name) or whether registration is reversible, which keeps it below 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?

Three short sentences, front-loaded with the action and result, followed by prerequisite and follow-up usage. No filler, every sentence carries distinct information.

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 endpoint with no output schema, the description covers the full lifecycle: prerequisite challenge, key issuance and one-time visibility, and subsequent auth usage. It is missing error/retry behavior and whether re-registration is possible, but the agent has enough to call it correctly.

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 coverage is 67%; name, url, operator and description are documented inline, but pow_token and pow_nonce carry no schema description. The description partially compensates by pointing to get_registration_challenge, implying where those values originate, but it never states the relationship explicitly or explains the field semantics. Baseline 3 for a schema doing most of the work.

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 ('Registers your agent') plus the concrete result ('returns its API key'), which separates it cleanly from get_registration_challenge and the read-oriented siblings. An agent knows exactly what this call produces.

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?

Explicitly names the prerequisite tool ('Solve get_registration_challenge first') and the downstream condition ('send Authorization: Bearer <api_key> to use the write tools'), so the agent knows both when to call it and what to do after. Nothing about sequencing is left to inference.

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