Drag Element to Structured Destination

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

Annotations already indicate destructiveHint=true, so the agent knows this is a mutating action. The description adds non-obvious context: 'failure-safe drag' and 'immediately before' imply that source/destination are resolved at drag time and that the operation is atomic or failure-tolerant. This goes beyond the structured annotations without contradicting them.

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 exactly two sentences. The first sentence states the core function using a specific verb and destination types. The second sentence adds scope and a usage alternative. No word is wasted, and the most important information is front-loaded.

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?

Given the tool's high complexity (discriminated unions, nested selectors, shadow DOM) and the presence of an output schema, the description adequately covers the core use case, the supported environments, and an alternative. It does not explain failure modes or the exact semantics of 'track-ratio', but those are partly recoverable from the schema's definitions, so the description is sufficiently complete for an agent to select and attempt invocation.

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 reported at 0%, so the description carries the burden of explaining parameters. It does name the destination union types (element, offset, track-ratio) and mentions CSS/XPath scope (iframe, shadow DOM), which adds meaning to selector/frame_selector/shadow_hosts. However, it does not elaborate on 'button' or 'profile', and the track-ratio mechanism is left ambiguous. Overall it partially compensates for low schema coverage but is not comprehensive.

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 clearly identifies the tool's function: resolving a source element and a structured destination (element, offset, or track-ratio) before performing a drag. It also distinguishes itself from a coordinate-based drag tool by explicitly mentioning 'use coordinate drag for visual-only targets', making it distinct from siblings like page_pointer_drag.

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 description provides explicit guidance on when to use this tool: when an element-based drag is needed, including in iframes and Shadow DOM. It also gives a clear alternative: 'use coordinate drag for visual-only targets'. This directly addresses when not to use this tool, satisfying the 'explicit when/when-not/alternatives' criterion.

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