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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description does add real context beyond that: the id is never invented server-side and the tool returns participants rather than messages. It stops short of describing the shape of the participant list (ids vs names, ordering, pagination), which a caller would still want.

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?

Front-loaded with the action, then provenance, then the exclusion. Four short sentences with no filler, though the parenthetical definition of a chat is slightly verbose relative to its payoff.

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?

With no output schema, the description correctly compensates by saying it returns participants and not message history. Annotations cover safety and determinism. The only remaining gap is the concrete return shape of the member list.

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% and the single parameter's schema description already states the bubble_id provenance and that it is required, so the description largely restates it. The only marginal addition is the behavioral note that the server never synthesizes a default. Baseline 3 applies when the schema does the heavy lifting.

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 and resource ("List who is in a chat") and pins down the scope with a definition of a chat as "a session that holds other sessions," which disambiguates it from list_chats and list_agents. An agent can tell exactly what this returns without opening the schema.

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?

Names where the `chat` value must come from (create_chat or list_chats), rules out an implicit chat ("no connection has an implicit chat"), and explicitly routes the adjacent need elsewhere: "It does not return message history — use check_agent_output." That is an explicit when/when-not with a named alternative.

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