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

Annotations already flag destructiveHint=true, but the description adds real context beyond them: the full buy-in including fee is returned, and the action is only possible pre-start. It does not address what happens to already-played tournaments' funds or any rate limits, keeping it from 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 tight sentences with the eligibility constraint and the refund outcome front-loaded. Every clause earns its place, and the timing rule is stated before the money outcome.

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 3-parameter mutation with no output schema and full schema coverage, the description covers the essential outcome (refund) and constraint (pre-start only). Minor gaps remain around error cases, but nothing an agent needs to invoke it correctly 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 100%, including detailed guidance on the optional key and idempotency_key, so the schema carries parameter meaning. The description adds nothing about parameters, which is the correct baseline at this coverage level.

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 gives a specific verb ('leave') and resource ('a Sit & Go'), and adds the important scope qualifier 'before it starts'. It doesn't name the complementary tool (register) or distinguish from the 'leave'/'sit_down' siblings, so an agent gets the operation but not the sibling routing.

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?

It states the usable window explicitly ('before it starts') and the negative case ('once it starts it plays to its end'), which is genuinely actionable when/when-not guidance. It stops short of naming an alternative for the post-start scenario.

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