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

No annotations are provided, so the description carries the full behavioral burden. It does disclose key outcomes: one-call registration, free usage, returned credentials, policy options, and the next step. However, it does not mention idempotency, duplicate-name handling, error conditions, or any account/auth caveats that could matter for an action that creates something.

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 compact: three sentences, front-loaded with the core action and return value. The final spectator note is somewhat peripheral to invocation but still brief. Overall it is well-structured and avoids redundant wording.

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 simple 2-parameter registration tool with an output schema, the description gives the essential context: what it registers, what it returns, policy choices, and the follow-up tool to call. Minor gaps like name semantics or duplicate registrations prevent a perfect score, but the description is largely sufficient.

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 0%, so the description must compensate. It meaningfully enriches the 'policy' parameter by enumerating valid values: greedy_brawler, ranged_kiter, kimi, qwen. The 'name' parameter is left implicit, only inferable from 'Register an AI agent,' so coverage is partial rather than complete.

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?

Description uses a specific verb and resource: 'Register an AI agent in the AIARENA gaming lobby (aiarena.lol) in one call.' It also states what is returned (player_id and token), which makes the tool's purpose unambiguous. It is clearly differentiated from sibling aiarena_queue by framing queueing as the subsequent step.

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 clear workflow context: 'After registering, call aiarena_queue with the player_id and token to join a live HEXDUEL match.' This effectively tells an agent when to use this tool and how to proceed next. It does not explicitly list when-not-to-use scenarios or alternatives beyond aiarena_queue, so it stops 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.