End a session

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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered; the description adds genuinely useful context beyond that by distinguishing the two termination modes — a headless session stops taking turns, while a live window merely disconnects and stays open on the Mac. It stops short of saying whether an ended session can be resumed or what happens to in-flight work.

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, the action front-loaded and the behavioral distinction second; nothing is wasted or restated.

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 one-parameter mutation with no output schema and annotations covering safety and idempotency, the description supplies the key behavioral consequence for each session type. Only the origin of session_id and post-close state are left implicit.

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 session_id parameter has 0% schema description coverage and the description never explains its format or that it comes from start_session/list_sessions. The name is largely self-evident, but with low coverage the description should compensate and does not.

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 ('Close a session') and immediately splits the outcome by session type, so an agent learns this is the counterpart to start_session in the sibling set. It does not explicitly name start_session or cancel_job as the inverse/alternative, which keeps it just under a 5.

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?

Usage is only implied: the description makes clear this is how you terminate a session, but it never says when to prefer it over cancel_job for a running job, nor what preconditions exist (e.g., must the session be idle).

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