browser_toolbar_widgetsLists widget IDs in a specified Firefox toolbar area, defaulting to the main nav-bar, to help identify toolbar widgets before managing or customizing them.
List the widget ids currently in a toolbar area (privileged context). Use area "nav-bar" for the main toolbar.
| Name | Required | Description | Default |
|---|---|---|---|
| area | No | Toolbar area id, default "nav-bar" |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds one genuinely useful trait — '(privileged context)' — signaling it may require elevated privileges, plus 'currently' implying live state. It does not say what happens if the area id is unknown or how many widgets come back.
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 short sentences, zero filler, with the core action front-loaded and the parameter hint trailing. Nothing to trim.
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 zero-required-parameter read tool with no output schema, the description tells the agent what it returns (widget ids) and what the main area is called. Only the return shape (array? count?) and behavior on invalid areas are left implicit.
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% and the single parameter already has a description and default of 'nav-bar', so the schema does the heavy lifting. The description's example of 'nav-bar' for the main toolbar is mildly additive but does not enumerate valid area ids beyond the default.
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 verb and resource: 'List the widget ids currently in a toolbar area.' An agent can tell it returns widget identifiers for a toolbar region, but it never contrasts itself with the closely related browser_get_toolbar_layout or browser_set_toolbar_widget 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?
The guidance given ('Use area "nav-bar" for the main toolbar') is about parameter values, not about when to choose this tool over browser_get_toolbar_layout or the setter siblings. Usage is implied by the read-only listing framing, but no exclusions or alternatives are named.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.