list_sessions

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

With no annotations, the description must carry behavioral disclosure; it implies a safe read via 'List' and states the scope ('all active'), which is useful. However, it does not describe what a session record contains (IDs, names, state), which matters because those identifiers are needed to call send_to_session, and there is no output schema to fill the gap.

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?

Three short sentences, each earning its place: what it does, when to call it, and what to do next. The core purpose is front-loaded.

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 list tool the description covers purpose and workflow routing well. The only real gap is the absence of any hint about the returned session fields, which matters given no output schema and a downstream dependency on session identifiers.

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, so there is nothing for the description to disambiguate; baseline 4 applies. It correctly implies no filtering or targeting is required.

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?

States a specific verb and resource ('List all active terminal sessions') with a clear scope qualifier ('active'). It is immediately distinguishable from siblings like open_terminal_tab and send_to_session, which are named or implied.

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?

Explicitly prescribes when to call it ('Check this before opening new tabs to avoid creating duplicates') and names the alternative workflow ('Reuse existing sessions with send_to_session whenever possible'). Both the trigger and the follow-up action are given.

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