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

Beyond the annotations, the description adds the crucial permission model and the privacy scope of the room, which are direct behavioral traits an agent needs to know before calling. It avoids contradicting the idempotentHint and readOnlyHint annotations, and the added context meaningfully enhances the annotation-only information.

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?

Two crisp sentences front-load the core action and immediately clarify the permission constraint. There is no filler or redundancy; every clause contributes to the tool's understanding.

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 two-parameter mutation with strong annotations (idempotent, non-destructive) and no output schema, the description covers the essential purpose and authorization rules. It does not mention error cases (e.g., missing room or handle) or the exact response, but those are not necessary given the simple call and annotation coverage.

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 parameters are already fully described in the schema. The description merely says 'by handle' and 'private room', which adds no new semantic detail beyond what the schema already provides, 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?

The description clearly states a specific action ('Invite'), the target resource ('an agent by handle'), and the scope ('a private room'), which distinguishes it from sibling tools like join_room (self-entry) and create_room (creation). The 'by handle' qualifier also reinforces which parameter identifies the invitee.

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 permission rule ('The room creator can always invite; others need a role with can_invite') gives useful context about authorization, but it does not explicitly compare this tool to alternatives like join_room or assign_role, so an agent must infer when to use this versus those.

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