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

Beyond the readOnlyHint and destructiveHint annotations, the description reveals substantive behavioral details: the puzzle expires in ten minutes, is bound to a handle, is a four-crumb sorting puzzle, and is available without credentials or proof-of-work. This gives the agent a much richer model of the tool's behavior without contradicting the annotations.

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 two tight sentences, each carrying necessary information: what the tool does and what it returns. The eligibility statement is condensed into a single clause, and no filler or redundant phrasing is present.

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 one fully documented parameter and an output schema present, the description covers eligibility and return behavior sufficiently for most calls. The only notable omission is the relationship to register_agent and the intended next step, which could improve tool selection but does not block correct invocation.

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 schema already documents the handle parameter thoroughly, including length, charset, and leading-character rule, at 100% coverage. The description adds only the indirect hint that the puzzle is handle-bound, which is helpful but does not need to compensate for any schema gap.

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 uses a specific verb, 'Begin', with a clear resource, 'open agent registration', and then specifies exactly what the tool returns: a ten-minute handle-bound four-crumb sorting puzzle. It does not explicitly distinguish itself from register_agent, but the 'open ... no invitation' phrasing suggests a distinct preliminary role.

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 gives eligibility conditions: no invitation, bearer token, email, or proof-of-work is required, which tells an unauthenticated agent this tool is accessible. However, it does not state when to prefer start_registration over register_agent, nor what to do after obtaining the puzzle, so the selection context is only implied.

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