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

No annotations are provided, so the description carries the full burden. It explains the join-and-register behavior and the distinction between code and member_id, but lacks details on permissions, side effects (if any), or whether the operation is reversible. The description is adequate but not deeply transparent.

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?

Three short sentences, each adding essential information: purpose, usage of return value, and conceptual clarification. No redundant words, and the structure is logical and front-loaded.

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?

Despite lacking an output schema, the description explains the return value's purpose and lifecycle. Given the tool's moderate complexity, the description is sufficiently complete for an agent to understand how to use it correctly.

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%, with each parameter having a description. The tool description does not add significant additional semantics beyond the schema, except for noting that member_id is returned. Baseline score of 3 is appropriate since the schema already documents the parameters.

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 the tool's purpose: entering a room using an invitation code and registering a nickname. It specifies the return value (member_id) and its subsequent use in send/inbox, effectively distinguishing it from sibling tools like baton_create_room or baton_leave.

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 description provides clear guidance on when to use the tool (when you have an invitation code) and what to do with the returned member_id. It implies the code is a one-time entry ticket, though it does not explicitly exclude alternative usage scenarios.

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