cdp_scrollScroll a browser page by wheel deltas via CDP; use positive delta_y to scroll down and delta_x to scroll right.
Scroll the page by a wheel delta (positive delta_y = down).
| Name | Required | Description | Default |
|---|---|---|---|
| port | No | CDP debug port (default 9222). | |
| delta_x | No | Horizontal wheel delta: positive scrolls right | |
| delta_y | No | Wheel delta: positive scrolls down |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false and destructiveHint=true, so the safety profile is covered. The description adds only the directionality of delta_y, which is already documented in the schema, and says nothing about side effects, required CDP attachment, or what 'destructive' means for a scroll operation.
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 a single, front-loaded sentence with no wasted words. It states the action and the key directional convention 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 three-parameter tool with full schema descriptions and safety annotations, the description is minimally adequate. However, it omits context about CDP attachment requirements and how it relates to the alternative desktop_scroll 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?
Schema description coverage is 100%, so all three parameters are fully documented in the schema. The description repeats the delta_y direction from the schema and adds no extra syntax, default, or unit information.
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 ('Scroll the page') and clarifies the effect of delta_y. It does not differentiate this tool from the sibling desktop_scroll or otherwise situate it within the CDP family.
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?
No guidance is given about when to use this tool versus alternatives such as desktop_scroll, nor are any prerequisites or exclusions mentioned. The description only states what the tool does, not when it should be selected.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.