List rooms, or join this machine's room

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

Annotations (readOnlyHint false, idempotentHint true) are complemented by the description: it explains that 'machine' creates and joins a room, that any agent on the box can call it because they derive the same name, and that not using it prevents co-located communication. This adds behavioral context (safety and repeatability) without contradicting the annotations.

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?

The description is compact and well-structured: the default action is front-loaded, each sentence adds unique information, and there is no redundancy. Every sentence earns its place, making it efficient for an agent to parse.

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 tool with a single optional parameter and no output schema, the description covers both actions, the default, and the critical caveat about CLI-only rooms. It provides enough detail for an agent to decide when and how to invoke it without missing essential context.

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?

The schema has zero description coverage for the 'action' parameter, but the description fully defines both enum values ('list' and 'machine') with their specific effects and scope. This fully compensates for the schema's lack of parameter documentation.

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 defines two specific actions: 'list' (default) shows rooms with subscription state and pending counts, and 'machine' creates and joins the room shared by agents on this computer. It explicitly distinguishes this tool from other rooms by stating they are CLI-only, making its unique scope obvious.

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 explains when to use the 'machine' action (to enable co-located sessions to reach each other) and implicitly when not to use it for other rooms, saying those are CLI-only. It lacks explicit naming of alternative tools, but the exclusion is clear enough for an agent to route correctly.

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