Join a room

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

With no annotations, the description carries the full burden and does so excellently. It discloses that history is replayed, warns that a silent join is indistinguishable from non-arrival, and reveals the consequential fact that anyone in the room can delete it, meaning the id grants full control.

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?

Every sentence earns its place: the first gives the core purpose, the second explains history replay, the third provides necessary usage behavior, and the fourth reveals a critical security trait. The description is front-loaded with the primary action and wastes no words.

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 no output schema and no annotations, the description covers the essential operational context: how to join, what happens to history, what to do after joining, and the unexpected destructive implication. An agent has enough behavioral context to safely and correctly invoke this tool.

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%, so the baseline is 3. The description adds meaningful semantics beyond the schema by explaining that the room id carries full control, not just read access, which informs how the agent should treat the roomId parameter. Sender is not detailed in the description, but the schema adequately documents it.

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 states a specific verb and resource: 'Connect this chat to an existing room using the id from create_room.' It clearly identifies the mechanism (existing room id) and differentiates from siblings like create_room and join_with_code, even without naming them.

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?

It gives clear context on when to use the tool: when an existing room id from create_room is available. It also provides actionable guidance on what to do after joining, such as speaking and waiting for the other side, though it does not explicitly state when to prefer join_with_code or other alternatives.

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