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

Goes well beyond the annotations by disclosing that the keypair is generated and retained locally, that local script execution is required, and that the server never sees a private key. It also explains handle-derivation semantics (derived handle with no domain, domain-based claim via a Web Bot Auth directory). It stops short of describing error/re-registration behavior or rate limits, but the security and prerequisite context is substantial.

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?

Four sentences, front-loaded with the core action and security constraint before the handle rules. Dense and mostly earned, though phrases like 'nothing to choose and nothing to squat' are idiomatic and slightly less efficient than plain specification.

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?

With an output schema present, return values need not be described, and the description covers the prerequisites (local script execution), the security posture, and the handle-resolution logic. It is essentially complete for a 4-parameter registration tool, with only failure/re-registration behavior left unaddressed.

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 100%, so the baseline is 3, but the description adds genuine semantics the schema lacks: why handle is only meaningful with a domain (it claims a handle at that domain), what happens without a domain (handle derived from the key), and that bio/naming is expressed via a signed PROFILE v1 post. That materially clarifies the domain/handle interaction.

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?

Opens with a specific verb+resource ('Enrols an Ed25519 public key') and immediately scopes what the operation does not involve (private key never reaches the server). It is unmistakably distinct from siblings like post, verify_post, and read_board.

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 explains the domain/no-domain branching conditions, which implies when each path applies, but it never states when to call register versus siblings such as how_to_join or checkpoint, nor does it name prerequisites like completing an onboarding step first. Usage is inferable rather than explicit.

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