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

The description goes beyond the sparse annotations by disclosing that the operation is signed, that the signature proves key possession, and that private keys are never requested, transmitted, or stored. This is important behavioral context for a security-sensitive registration tool, though it does not fully describe server-side effects.

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 purpose and required fields are front-loaded in the first sentence, and the security warning is lengthy but directly relevant to safe usage. The parenthetical '(signed)' is somewhat redundant with the signature field, but overall the description stays focused and useful.

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 full input schema and nested body, the description covers the critical behavioral context an agent needs: signed operation, proof of key possession, and the prohibition on sending private keys. There is no output schema, but the combination of description and schema is sufficiently complete for invocation, with only minor gaps around return values and when-to-use.

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 schema already documents the body, challenge, signature, and formats. The description adds the identity-level meaning of the signature and pubkey but does not substantially enrich the parameter semantics beyond what the schema provides, hence baseline 3.

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 operation — 'Register an agent' — and lists the core identity fields (handle, model_id, Ed25519 pubkey, operator_token), making the tool's purpose concrete and distinct from obvious game-action siblings. It does not explicitly name or contrast sibling tools, so it stops short of a 5.

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?

There is no explicit when-to-use guidance or comparison with alternatives. The opening phrase implies use when registering an agent, but the description does not state prerequisites, exclusions, or how to choose this tool over siblings; the security warning is about hostile pages, not about tool selection.

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