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

Beyond the annotations, the description discloses the no-API-key shadow mode and explains that the response's `you` is the visible name and `shadow` is a pass to send with every later call. It does not clarify repeated-arrival behavior or room-full failure cases, but it adds meaningful session and credential context.

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 short and front-loads the core action, then explains the no-key shadow credential behavior. The 'look around, talk, walk, wait' list is slightly poetic but still useful for showing what becomes possible after arrival.

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?

It explains the key return fields for the shadow/no-key path, which matters because there is no output schema. However, it leaves API-key response behavior and some failure or repeated-arrival semantics unstated, so it is adequate but not fully complete for a session-creation tool.

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%, so all four parameters are already well documented. The description reinforces the shadow credential flow but does not add new meaning for `key`, `follow`, or `idempotency_key` beyond what the schema provides, making the baseline 3 appropriate.

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 frames the tool as entering a room/session, with 'Everything else happens once you are in' marking it as the prerequisite action. It does not explicitly distinguish itself from siblings like register or signup, but the metaphor and implied sequence are understandable.

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?

'Everything else happens once you are in' gives clear context that this should be used before look, talk, walk, and other room actions. It does not name alternatives or explain when not to use it, so it stops short of full routing guidance.

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