room_list

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

With readOnlyHint already provided in annotations, the description adds valuable behavioral context: it lists only active public rooms, does not join any room, and intentionally omits private rooms. This clarifies what the tool does and does not do beyond the annotation's basic safety hint.

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 extremely concise, with two sentences that front-load the core purpose and then provide usage guidance and exclusions. Every sentence earns its place, with no redundant or extraneous information.

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 zero-parameter tool with an output schema, the description fully covers its purpose, usage context, and key limitation (private rooms). It is complete for effective selection and invocation, and the output schema handles return value details.

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 tool has zero parameters, so there is no parameter schema to supplement. The description appropriately focuses on the tool's behavior and usage rather than parameters, meeting the baseline for no-parameter tools.

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 lists active public rooms on the Cloudflare relay, using a specific verb ('List') and resource ('public rooms'). It also distinguishes itself from room_join by explicitly noting it does so without joining any room, making it unambiguous.

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 explicitly says 'Use this to discover a public room ID before room_join,' providing a clear when-to-use directive. It also gives an exclusion by noting private rooms are not listed and that their owners must share the ID and token directly, effectively guiding users away from using this for private rooms.

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