list_sessions

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

Annotations already declare readOnlyHint=true and idempotentHint=true, covering the safety profile. The description adds only the 'active' filter and 'details' output, but does not disclose behavior such as whether all sessions are returned, ordering, or the meaning of 'active'. No contradiction with 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 a single sentence that is front-loaded with the action and resource. Every word is necessary, and no filler exists. It is as concise as appropriate for a simple list tool.

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?

The output schema covers return value structure, and annotations cover the read-only nature. However, the description fails to explain the 'target' parameter or clarify what 'active' means, leaving uncertainty about filtering behavior. For a simple tool this is borderline complete, but the parameter omission detracts.

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 single optional parameter 'target' has zero schema description coverage, and the description provides no explanation of its purpose. The agent cannot infer how to use 'target' from the description or schema, forcing reliance on prior knowledge. This is a significant gap for a parameterized 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 identifies the resource 'tmux sessions' with scope 'active' and output detail 'with details', clearly distinguishing it from sibling tools like get_session (single session) and list_windows (different resource).

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 state when to use this tool versus alternatives like get_session or list_windows. It implies usage for listing sessions but lacks any exclusions or alternative references. Given the simplicity of the tool, this is adequate but not exemplary.

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