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

Beyond the annotations, the description adds valuable behavioral context: moves are persisted, cannot be undone, and depend on the current revision. This helps the agent treat the call as consequential. It does not mention output or error behavior, but the irreversibility warning is a strong disclosure.

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 sentences with no filler. The primary action is front-loaded, followed by essential caveats, making it easy for an agent to parse quickly.

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 mutating tool with a complex move schema and no output schema, the description lacks any statement about the response shape, error conditions, or how to obtain a valid session and revision. It partially compensates by telling the agent to re-read game state if the revision is stale, but significant operational context is missing.

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%, and the description does not explain sessionId, sessionToken, or the move structure itself. It only partially clarifies the revision parameter through the stale-revision guidance. The rich move schema is self-explanatory, but the description adds little parameter-level meaning.

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 a specific verb and resource: 'Apply one validated move at the current revision.' The title and name align, and the action is easily distinguished from siblings like arcade_read_game or arcade_start_game.

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 contextual guidance by warning about stale revisions and instructing the agent to read the game state again before retrying. It does not explicitly name alternatives or say when not to use the tool, but the usage context is reasonably clear.

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