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

With only readOnlyHint=false provided, the description usefully adds that the pending challenge has no timeout, so cancellation stays possible indefinitely until an answer arrives. It does not say what happens to the pending challenge record after cancellation, nor whether cancelling after an answer fails with an error.

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?

A single front-loaded sentence with the action first and the condition second; no filler or redundant restatement of the tool name.

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 zero-parameter tool with no output schema this is close to sufficient, but the agent is left unsure of the success/failure outcome (e.g., behaviour when the target already answered) and whether anything else is affected by the cancellation.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; baseline for 0 params applies. The description correctly does not invent parameter detail.

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 states a specific verb and resource ('Отменить свой вызов на дуэль'), making the mutation target unambiguous. It implicitly separates this from game_duel_challenge (creation) and game_duel_answer (responding) through the word 'cancel', though it never names either sibling.

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 precondition 'пока цель не ответила' clearly defines the window in which this tool is valid, which effectively tells the agent when not to use it. It does not name an alternative action (e.g., game_duel_answer) for the case where the target has already responded.

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