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

Annotations cover the safety profile (openWorldHint true, idempotentHint false, destructiveHint false), and the description adds genuinely non-derivable context: the seat model, the invite-link handling rule ('Send the invite only to that person'), and an auth constraint. The auth detail is especially valuable because it states the key goes in an Authorization: Bearer header, not as an argument.

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?

Four tight sentences, front-loaded with the action and the seat/invite outcome before the usage condition and the auth note. No filler or redundant restatement of the title.

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 still conveys what the agent gets back (a private invite link) and how to handle it, plus the sign-in requirement. What is missing is minor: no mention of expiry, limits on room count, or passcode behavior beyond the schema hint.

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 the schema already documents all five parameters including the enum for counterpart_proxy. The description adds conceptual context (seats, invite link) but no per-parameter syntax or format detail, so the baseline of 3 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?

States a specific verb and resource ('Open a new room') and immediately clarifies the resulting state: the principal takes seat A and the agent receives an invite link for seat B. This distinguishes it cleanly from siblings like get_room, join_room, and answer_escalation without opening their schemas.

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?

Gives an explicit trigger condition: 'Use this when your principal wants to negotiate with someone and has no room yet.' The 'no room yet' clause implicitly routes the agent away from join_room, but no sibling is named directly, which keeps it short of a full 5.

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