x_session_close

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

Annotations are all false and provide no behavioral signal, so the description carries the burden. It discloses meaningful behavior: closing the browser/tab, discarding prepared actions, and persisting login in the local profile. It does not contradict annotations, though it could add reversibility or failure-condition details.

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 focused sentences with the primary action first and the persistence caveat second. No filler, repetition, or unnecessary detail.

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 no-parameter close operation, the description adequately covers what happens and the key persistent-login caveat. It does not mention return values or behavior when no session exists, but those are minor for such a simple operation.

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 has zero parameters and the schema is empty. With no parameters to explain, the description cannot add parameter-level value, so the baseline of 4 is appropriate.

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 action ('Close the MCP-owned browser/tab') and a clear side effect ('discard prepared actions'). This distinguishes it from sibling tools like x_session_status, x_session_open, and x_action_cancel.

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?

No explicit guidance on when to use this tool vs alternatives. It does not mention 'use instead of x_action_cancel' for discarding prepared actions, nor does it state prerequisites like requiring an active session. Usage context is only implied by the name and description.

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