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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, yet the description still adds real behavioral context: it discloses that shape of returned data (presence, former members, join log) and crucially that pending-join visibility is gated on the caller being the room owner. It does not cover pagination or overall permission requirements.

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?

A single dense sentence that front-loads the verb and packs the return contents into a clean parallel list with zero filler. Slightly long, but every clause corresponds to distinct returned data rather than restating the 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 simple read-only listing tool with annotations covering safety and no output schema, the description covers what is returned reasonably well. It omits permission requirements beyond owner-gating, any mention of result size or truncation for large rooms, and any explanation of member_token, leaving gaps an agent would want filled.

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% and both required parameters (room_id, member_token) are undocumented in the schema. The description never mentions either parameter or explains what member_token represents, so it fails to compensate for the coverage gap.

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 (List) and resource (a room's members) and enumerates the four content categories returned: presence, pending joins, former members, and the join log. It does not explicitly differentiate itself from siblings like room_read or room_manage, so an agent must infer the distinction, but the purpose itself is unambiguous.

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?

There is no statement of when to use this over room_read, room_manage, or the other room_* siblings. The only conditional in the description ('pending joins if you are the owner') governs what data is returned, not when to invoke the tool, so no routing guidance is provided.

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