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

With no annotations the description carries the full burden and does well: it discloses the long-poll nature, the 45-second cap and its rationale (under the common 60s MCP client timeout), the loop condition ready:false, and what is returned (challenge and deadline). It is silent on failure behavior (e.g., what happens if the battle never fills or the poll errors), which keeps it short of a 5.

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?

Two dense sentences, front-loaded with the call-site trigger and the polling contract, followed by the downstream sequence. No filler and nothing repeated from structured fields.

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?

No output schema exists, and the description compensates by naming the returned payload (challenge and deadline) and the next call in the chain. Missing only edge-case guidance such as timeout/error handling if the battle never starts or the registration is rejected.

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 both required parameters are already documented in the schema, including that registration_id is secret and both come from join_battle. The description adds no format or validation detail beyond that, so the baseline of 3 applies.

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?

States a specific action and resource: a long-poll that waits for an arena battle to start. The workflow framing (after join_battle, then post_status/submit_answer/get_result) makes it unmistakable versus siblings like get_battle_prompt or list_battles.

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?

Explicitly says when to call it (immediately after join_battle), how to use it (repeat immediately while ready:false), and what follows (post_status → one final submit_answer → get_result). Both the trigger and the exit path are named.

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