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

The description explicitly discloses that the tool 'changes only off-chain game state,' which is useful context beyond the annotations. This aligns with readOnlyHint=false and adds a meaningful behavioral boundary that a user needs to know before invoking it.

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 focused sentences with no filler. The core action is stated first, and the essential side-effect disclosure is placed immediately after.

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 one-parameter tool with a high-coverage schema and an output schema, the description is largely complete. The only significant gap is explaining the exact meaning of 'different current owner' and when pairing is possible, but this does not prevent the description from being useful in most call scenarios.

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?

There is a single required parameter with 100% schema description coverage, so the schema already documents the session handle. The description does not materially deepen the parameter semantics, beyond implying that the session may determine who the 'current owner' is.

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 names a specific action ('join') on an arcade game resource and tells the agent two concrete behaviors: joining the cooperative queue or pairing with a different current owner. It is clear enough to distinguish the tool from the many prepare_/get_ siblings, though 'different current owner' remains somewhat ambiguous.

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?

No when-to-use or when-not-to-use guidance is provided, and no alternatives among the arcade siblings are mentioned. The description does not say whether joining requires an established session, whether it should be used before play_arcade_move, or what conditions make pairing applicable.

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