List sessions

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

With readOnlyHint and destructiveHint already covering safety, the description adds non-obvious behavioral facts: this operation does not launch a browser and does not discover unrelated user tabs. That goes beyond the annotations and clarifies the tool's limited scope.

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?

Two short sentences with no filler. The positive statement comes first and the behavioral exclusions are packed into a second sentence that earns its place.

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 parameterless, read-only listing tool with annotations covering safety, the description is sufficient: it states the returned resource and the key non-behaviors. No output schema exists, but the absence of parameters makes the call surface fully clear.

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 takes zero parameters and schema coverage is 100%, so there is no parameter documentation burden for the description. The baseline of 4 applies; no additional parameter semantics are needed.

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 names a concrete action and resource ('List the sessions owned by this server') and adds negative scope ('Does not launch a browser...'), making the intent unambiguous. It is not a restatement of the title or name, and it differentiates from tab-discovery tools.

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 a clear context: use when a server-owned session listing is needed, and it explicitly excludes browser launching and unrelated user tab discovery. It stops short of naming an alternative sibling tool (e.g., tab_tabs), so the when-not is implicit rather than pointing to a specific replacement.

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