Close session

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

With no annotations, the description carries the full burden of behavioral disclosure. It transparently describes destructive effects: page state and cookies are gone, the history file is finalized, and the session's history is archived rather than overwritten. It also explains the behavior for an unknown id, which is valuable edge-case information.

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 sentences, each earning its place: primary effect, error return behavior, and lifecycle caveat. No filler or repetition of the schema. The most important action is stated first.

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 description is thorough for a single-parameter tool with no output schema, covering effects, error behavior, and post-close lifecycle. The only minor gap is that it does not explicitly state the success return value or shape, though it is largely inferable from the unknown-id behavior.

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 coverage is 100%, so the baseline is 3. The description adds meaningful parameter-related behavior by explaining what happens when the sessionId is unknown (returns closed:false and active sessions). This goes beyond the schema's simple type and description, aiding correct invocation and error handling.

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 specific verbs ('Stops', 'terminates') and identifies the exact resource (a session and its browser context). It clearly distinguishes itself from sibling tools like start_session by defining the lifecycle relationship. This is unambiguous and actionable.

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 provides clear context about when to use the tool: when a session should be ended and its browser context cleaned up. It also notes that a closed session can be restarted later, which helps the agent understand the lifecycle. It does not explicitly name alternatives or exclusions, but no close alternative exists among siblings.

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