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

With no annotations at all, the description carries the full burden and does well: it discloses that the server is authoritative ("seeds and replays all controls"), that scores are not client-reported, and that requestId makes retries idempotent. Left unstated are failure modes (what happens without permission, or starting an already-active session) and any rate limits.

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?

Six short sentences, each carrying a distinct fact, with the permission prerequisite front-loaded. No filler or 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 two-parameter session-start tool with no annotations and no output schema, the description covers the inputs, the server-authority model, idempotency, and the rough return shape ("session state and timing/control rules"). A little more on error/permission behavior would make it fully self-sufficient.

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%, so the description must compensate. It names all three accepted game values and explains requestId's purpose (reuse on retries, i.e. dedupe key), which is real added meaning, but it does not explain the UUID format constraint that the schema enforces or what constitutes a valid retry window.

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 ("Start") and enumerates the three concrete game slugs (soap-dodge, chalupa-catch, plunger-pong), which map directly to the enum. It also clarifies the boundary against a finished game ("Start is not a completed play"), though it never names the sibling tools it hands off to (bathroom_game_input, bathroom_game_status, bathroom_game_finish).

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 a clear precondition ("Requires play permission") that an agent must satisfy before calling, and implies the session continues elsewhere since a start is not a completed play. It stops short of explicitly routing to bathroom_game_input/status/finish or saying when not to start a new session.

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