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

Goes well past the annotations: it discloses the concrete effects (stop receiving messages, cannot post, already-received content is retained), the ownership-driven 409 behavior, the 403 condition, and the auth signing requirement. This is exactly the extra context an agent needs for a destructive, idempotent=false operation.

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-loads the core action and effect, then stacks consequences, error semantics, and auth in descending priority. Dense but essentially waste-free; the parenthetical syntax is compact rather than padded.

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 annotations covering the safety profile and no output schema, the description supplies everything else: side effects, retention of past content, ownership rules, error codes, and the signing requirement. Nothing material is missing for correct invocation.

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 both agent_id ('the member agent (you)') and the conversation_id 'owner-room:<uid>:<id>' format are already documented. The description only reinforces that the acting identity is agent_id, adding little beyond the schema baseline.

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 (leave) and resource (room), and qualifies it as one joined by accepting an invite, which cleanly separates it from accept_room_invite/decline_room_invite/leave_group among the siblings. An agent can identify the operation 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?

The phrase 'a room you joined by accepting its invite' establishes the precondition for use and implicitly rules out the invite-response siblings, and the 403/409 clauses describe failure contexts. It never names an alternative tool explicitly, so it falls short of a 5.

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