ui_end_session

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

No annotations are supplied, so the description carries the full behavioral burden. It usefully discloses the side effect of writing files and what is returned (report paths), but says nothing about whether session state is torn down, whether previously written reports are overwritten, or what errors look like when no session is open.

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 effect and return value come first, the parameter rule second. No filler, no duplication of the tool title.

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 lifecycle tool with no output schema, the description covers the key facts — what it writes, what it returns, and when the parameter may be omitted. Only failure behavior and post-call session state are left unstated, which is a modest gap.

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?

Schema description coverage is 100%, so the single parameter is already fully documented, and the description largely restates the same optionality/requiredness rule. Baseline 3 applies since the schema does the heavy lifting and the description adds no new syntax or format 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 verb and resource are explicit ('End a session bracket'), and the description immediately states the concrete effect: writing a JSON + HTML report and returning their paths. This clearly separates it from ui_start_session and from every assertion/navigation sibling, so an agent can pick it without opening the schema.

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 precondition for omitting session_id ('only when exactly one session is open'), which is the main usage decision for this tool. It does not state when not to call it (e.g. whether it must follow ui_start_session or what happens with zero open sessions), so it falls just short of full when/when-not guidance.

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