browser_drag

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations exist, so the description carries the full burden and does disclose a genuinely important behavioral trait: the far end is not auto-scrolled into view, which will silently break drags. It also notes that a stale emsn is refused rather than clicked. It omits what a drag returns or how failures surface, keeping it below a 5.

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?

Three tight sentences, front-loaded with the gesture and then the constraint, with the critical on-screen requirement bolded. No sentence is filler.

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 14-parameter tool with no annotations and no output schema, the description covers the highest-risk failure mode (off-screen endpoint) and the destination-mode ambiguity. Defaults for holdMs/settleMs and the return behavior remain undocumented, so it is strong but not exhaustive.

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%, so baseline is 3. The description does add real value by stating the destination must be given 'exactly one way' across three mutually exclusive modes (toEmsn, toX/toY, dx/dy) — a constraint the schema itself does not encode — but the remaining parameters (holdMs, settleMs, button, tabId, windowId) are left entirely to the schema.

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?

Opens with a concrete verb sequence ('press on something, carry it somewhere, let go') and immediately differentiates from the sibling browser_click by naming the gesture a click cannot make. The enumerated use cases (sliders, canvas panning, split bars, reorderable lists) make the tool's domain unmistakable.

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?

Gives clear context for when to reach for this over browser_click and states a hard precondition: both endpoints must already be on screen, so scroll first. It stops short of naming browser_scroll as the explicit prerequisite tool, but the routing intent is unambiguous.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.