browser_session_listList active browser sessions to view tabs, fingerprints, and proxies for managing isolated environments.
List all active sessions with their tabs, fingerprints and proxies.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v2.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry the burden. The verb 'List' implies a read-only operation, but it does not explicitly state that it has no side effects, requires no authentication, or has any limitations. Since it returns session data, it effectively discloses its non-mutating nature, but it lacks explicit statements about side effects or conditions.
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?
One sentence, no filler, and the key information (listing active sessions) is front-loaded. Every word adds value, and it is appropriately terse for a simple list operation.
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 fully covers what the tool does and what it returns. A structured output schema exists, so the exact return format is already specified. For a no-argument list tool with low complexity, the description is complete—nothing an agent needs to call it correctly 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?
The tool has zero parameters, so the schema is trivially 100% covered. Per the baseline for 0-parameter tools, the description does not need to add parameter details. The description does not mention parameters, which is appropriate given there are none.
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 clearly states a specific verb ('List') and resource ('all active sessions') and explicitly enumerates the data included (tabs, fingerprints, proxies). This is unambiguous and distinguishes it from sibling tools like browser_session_new or browser_session_close, which have different purposes.
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 implies usage (use this to see active sessions) but does not provide explicit when-to-use guidance or contrast with alternatives like navigator_status. It is a simple list tool, so the purpose itself suggests when to use it, but no explicit exclusions or sibling differentiation are offered.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.