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

Annotations already declare destructiveHint=true, readOnlyHint=false and idempotentHint=false, so the safety profile is largely covered. The description adds real value by making the destruction concrete — in a running game you lose it — but says nothing about permissions, whether repeated calls error out, or what a caller observes afterward. With annotations carrying most of the weight, this is a modest but genuine addition.

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 sentence with no waste, front-loading the primary action and immediately qualifying the consequential case. Every clause earns its place.

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, non-idempotent mutation with no output schema, the definition covers what the tool does, the two lifecycle states it handles, and the destructive consequence, while annotations cover the safety hints. Only the post-call outcome and any error conditions remain unstated, which is a minor gap.

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?

With a single parameter at 100% schema description coverage, the schema fully documents game_id including its UUID format and its origin (the value join_arena returned). The description adds nothing about the parameter, which is acceptable at this coverage level but not additive.

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 verb (leave) and resource (game), and distinguishes two distinct modes: exiting a waiting room versus surrendering a running game. It is clearly separable from join_arena/join_table by polarity, though it never names a sibling explicitly.

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?

Gives clear contextual guidance: the outcome differs depending on whether the game is in a waiting room or already running, which is exactly what an agent needs to decide whether to call it. It stops short of naming alternatives (e.g. whether 'act' should be used instead to resign or abort) or stating when not to call it.

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