Capture a screenshot of an authorized Firefox tab through Firefox Bridge, requiring read and capture access; the image is discarded if navigation occurs during capture.
Capture an authorized tab. Every frame origin requires read and capture access. Discard the image if navigation occurs.
| Name | Required | Description | Default |
|---|---|---|---|
| tabId | Yes |
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, idempotentHint, openWorldHint, and destructiveHint=false. The description adds useful context about required read/capture access and discarding the image after navigation, but it does not describe the return format or other operational limits.
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 three short sentences and front-loads the core action. It is efficient, though the access sentence is dense and could be clearer.
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 low-complexity one-parameter tool with strong annotations, the description covers access and navigation invalidation. However, with no output schema, it omits what the screenshot returns and does not clarify the tabId parameter.
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?
There is one required parameter, tabId, with 0% schema description coverage. The description mentions an "authorized tab" but does not explain what tabId represents, how to obtain it, or any format constraints, so it does not compensate for the schema gap.
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 states a specific verb and resource: "Capture an authorized tab." The screenshot intent is clear from the tool name, but the description does not explicitly differentiate this from siblings such as firefox_read_page or firefox_inspect.
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 an access prerequisite and a navigation invalidation rule, but no guidance on when to use this tool versus alternatives or when not to use it. The agent must infer the usage context from the name and siblings.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.