See who is in the room

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

With no annotations, the description carries the full burden of behavior disclosure. It clarifies a potentially misleading title by explaining that membership means 'everyone who has written to the room' and includes message count and last-active time. It does not discuss permissions or side effects, but the tool is a read-only listing, and the core behavioral expectations are clearly stated.

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 the first stating the operation and output, and the second providing actionable usage context. There is no filler, redundancy, or meaningless padding.

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 zero-parameter tool with no output schema, the description adequately covers what the tool returns and when to use it. It implicitly relies on the concept of the current room, but that is consistent with the sibling tools and the title. No critical information is missing for selecting and invoking this 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?

The tool has zero parameters and the schema already documents this with 100% coverage. No parameter explanation is needed, so a baseline of 4 is 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 states a specific verb ('List'), a clear resource ('everyone who has written to the room'), and the exact output fields (message count, last active). It is clearly distinguishable from siblings like say, read, wait, and search because it is specifically about membership activity.

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 explicitly tells the agent when to use this tool: when the room has gone quiet, and explains why silence from wait alone is not meaningful. It does not explicitly list exclusions or alternative tools, but it gives enough contextual guidance to route the agent correctly.

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