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

Annotations already indicate readOnlyHint=false and destructiveHint=true. The description adds valuable behavioral details beyond these: the agent key is 'shown once,' the handle is 'owner-less' with 'no human account behind it,' and withdrawal is separate. It also clarifies free-tier behavior and earn-eligibility. However, it does not explain the destructiveHint=true annotation—there is no mention of what is destroyed or whether registration is irreversible—so it does not fully address the annotated risk. Still, it provides meaningful context and does not contradict annotations (no claim of non-destructiveness).

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 four sentences and front-loads the core purpose in the first sentence. It then provides essential follow-up details (key shown once, owner-less, withdrawal separate, free-tier status) in a logical order. While it is slightly longer than the minimal example (get_calls), each sentence contributes unique information. It is well-structured and not verbose, though a tighter version could combine some points. Score 4 reflects good balance.

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?

Given the tool's complexity (minting, key handling, ownership, withdrawal) and the absence of an output schema, the description covers many critical aspects: prerequisites (proof-of-work challenge), the immediate availability of free-tier queries, earn-eligibility, and the separate withdrawal step. It also clarifies the handle's owner-less nature and the one-time display of the agent key. However, it does not specify what the tool returns (e.g., the handle, the key), which would be helpful given no output schema. This minor gap prevents a 5.

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 input schema covers all parameters with descriptions (100% coverage), so the baseline is 3. The description does not add significant parameter-specific semantics beyond what the schema already provides—for example, it reiterates that the 'challenge' comes from register_autonomous_challenge but does not elaborate on the 'nonce' format or the meaning of 'requested_handle' beyond 'optional.' Since the schema does the heavy lifting, a score of 3 is 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?

The description clearly states the purpose: 'Complete keyless self-registration as your own ~alter principal by submitting a solved proof-of-work challenge.' It specifies the verb (complete/register), resource (self-registration as an ~alter principal), and references the sibling tool (register_autonomous_challenge), distinguishing this from the challenge-generation step. This is a specific and unambiguous statement of function.

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 provides clear context: it is the step following register_autonomous_challenge, and explicitly says 'Withdrawing is a separate step,' implying this tool does not handle withdrawal. It also mentions 'no human session' and 'no authentication required,' helping an agent understand when to use it. However, it does not explicitly state when not to use it or mention any alternative registration paths (e.g., human-assisted registration), so it falls 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.