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

With no annotations, the description carries the full burden. It discloses the side effect ('Frees the session') and the return content ('total steps, duration'), and even notes cost behavior ('Free, no token'). It does not mention irreversibility or ownership requirements, but the essentials are present.

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 the primary action and key outcome front-loaded. Every word earns its place; no fluff or repetition.

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 single-parameter, focused tool, the description covers purpose, behavior, side effect, and output summary. A slight gap is the lack of guidance about prerequisite state or where session_id comes from, but the tool is simple enough that this is not a serious omission.

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 only parameter, session_id, has 0% schema description coverage t: the schema just says it is a string. The description mentions 'session' but not how to obtain or format the ID. The parameter is self-explanatory, so no major issue, but the description adds no real semantic detail.

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 action ('Close'), the resource ('live session'), and the additional outcome ('get a short run summary'). It is distinct from siblings like session_start and session_step, making the tool's role 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 implies when to use it: when a live session needs to be closed, presumably after session work is complete. It does not explicitly name alternatives or exclusions, but the intended context is clear enough for an agent.

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