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

Annotations are all false, so the description carries the burden of explaining side effects and state changes. It adds valuable behavioral context: reserving an avatar slot, returning session credentials, and the fact that billing accrues while the session is open. This goes beyond what annotations state.

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?

The description is two sentences with no filler. The core purpose is front-loaded, followed by a critical billing/lifecycle warning, and the auth note is concise. Every sentence 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 tool with no output schema and a mutating side effect, the description covers the essential ground: what it does, what it returns, billing implications, and required auth. It does not enumerate error conditions or the full return payload, but given the schema coverage and annotations, this is not a critical 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?

Schema description coverage is 100%, so the input schema already documents all parameters. The description does not add meaningful parameter-level detail beyond noting that api_key comes from signup, which is marginal extra context.

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 clearly states the specific action: reserving an avatar slot and returning a client_token plus WebRTC connection info. The verb and resource are explicit墙, and the lifecycle contrast with end_session is immediately recognizable.

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 description gives clear operational guidance: billing is based on session duration and end_session should be called when done. It also notes the api_key requirement. It does not explicitly contrast with get_session or list_sessions, but the context is largely unambiguous.

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