Close a browser session opened with browser_open to release its browser after multi-step work, preventing idle sessions from keeping a browser running.
Close a session opened with browser_open and release its browser. Call it when the multi-step work is done; sessions left open keep a browser running.
| Name | Required | Description | Default |
|---|---|---|---|
| session_id | Yes | The `session_id` browser_open returned. |
Changes observed during successful MCP inspections.
v1.0.3Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false and openWorldHint=false, indicating a non-read-only local cleanup operation. The description adds useful behavioral context by explaining that the browser is released and that sessions left open keep a browser running. It does not cover error or idempotency behavior, but for this simple close operation that is a minor gap.
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 tightly written sentences with no filler. The primary action is front-loaded, and the usage condition and consequence follow immediately.
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 simple one-parameter cleanup tool with no output schema, the description covers the essential action, trigger, and resource consequence. Annotations supply the safety profile, and the schema supplies the parameter meaning, so nothing critical is missing.
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%, and the single session_id parameter is already documented in the schema as the value browser_open returned. The description reinforces that linkage but adds no format, validation, or edge-case meaning beyond the schema. Baseline 3 is appropriate when the schema carries parameter semantics.
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 names a specific verb and resource: close a session and release its browser. It explicitly ties the session to browser_open, distinguishing it from other browser-related siblings.
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 trigger condition: call it when multi-step work is done. It also explains the consequence of not calling it, with sessions left open keeping a browser running.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.