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

With annotations only flagging destructiveHint=true, the description explains the actual destructive semantics (it replaces any previous answer), the identity constraint, and the overflow behavior ('in' on a full game goes to the waitlist and the result reflects it). This is exactly the extra context annotations cannot carry.

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?

Three short sentences, front-loaded with the action, then identity scope, then the waitlist edge case. Every sentence carries distinct information with no repetition of the schema or title.

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 small 2-parameter mutation tool with annotations covering the safety profile, the description covers identity scope, overwrite behavior, and the full-game edge case. The only mild gap is that it doesn't explicitly state what the returned result contains beyond 'says so', though no output schema exists.

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 coverage is 100% and the enum plus the squadId cross-reference to list_squads are already documented. The description still adds meaning the schema lacks: what 'in' actually does when the game is full, i.e. waitlisting.

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+resource: recording the signed-in user's in/maybe/out answer for a squad's next game. That is clearly distinct from siblings like set_game (which configures the game) or join_squad (membership), so an agent can pick it without opening the schema.

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 context plus an exclusion: it acts only for the signed-in user and never on behalf of another player. It does not, however, name the alternative tool an agent should reach for when acting for someone else, so routing is still partly inferred.

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