List sessions that have an inbox

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 usefully discloses that only sessions with an inbox directory are listed, which is a behavioral filter. However, it does not explicitly state that the operation is read-only, nor does it describe the return format or potential side effects.

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?

One sentence, front-loaded with the verb and resource, no filler. Every word adds information, making it an efficient and well-structured description.

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, zero-parameter listing tool with no output schema, the description conveys what is listed and the defining criterion. It does not spell out the exact return shape or error behavior, but the complexity level makes this a minor gap.

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 input schema has zero properties, so there are no parameters to document. The description adds the only relevant semantic—the 'inbox directory' criterion—which provides enough meaning for a zero-parameter tool.

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 uses a specific verb ('List') and resource ('known session names') and adds the filter criterion '(those with an inbox directory)'. This clearly distinguishes it from sibling tools like bus_send and bus_receive, which handle messages rather than session enumeration.

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 does not explicitly name alternatives or exclusion conditions, but it gives clear context that this tool enumerates sessions rather than sending/receiving messages. The role in the bus tool family is self-evident, so an agent can infer when to use it.

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