Identify all active Firefox browser contexts to manage sessions and isolate testing environments during penetration testing.
List all active browser contexts.
This tool declares no required parameters. Add optional parameters from the input schema as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {},
"name": "list_contexts"
}
}| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the disclosure burden. It clearly scopes the operation to 'active' contexts and uses 'list', implying a read-only, non-mutating behavior. It could add return-format details, but for a zero-parameter list operation this is sufficiently transparent.
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?
The description is one short sentence with no filler. The verb, scope, and resource are front-loaded, and every word contributes meaning.
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 parameterless list tool with no output schema, the description is appropriately complete. It names the resource and the scope ('active'). Mentioning the exact return format would be a minor improvement, but the current description is adequate for such a simple tool.
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 an empty input schema. The baseline for no parameters is 4, and the description does not need to explain parameter semantics that do not exist.
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 a specific verb 'list' and a clear resource 'active browser contexts'. It distinguishes itself from sibling tools like new_context and close_browser, which create or close contexts rather than enumerate them.
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 phrase 'List all active browser contexts' implies when to use the tool: when you need an inventory of active contexts. However, it does not explicitly mention when not to use it or point to alternatives such as new_context or close_browser.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.