Drag and drop for HTML5 drag-and-drop targets

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

Goes well beyond readOnlyHint=false: it discloses the exact events synthesized, that the drop is simulated in page script rather than a real drag, the underlying BiDi/Firefox limitation and upstream bug, and the resulting failure modes. This is exactly the side-effect context an agent needs before attempting a drag.

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?

Front-loads the action, then the rationale and caveats in clearly labeled clauses; dense but every part is relevant. Mild redundancy in restating the upstream-bug rationale at the end costs it a point.

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?

No output schema exists, but the description makes clear what the tool does and does not achieve, and what kinds of pages it will fail on — everything an agent needs to decide whether to call it or fall back to browser_drag.

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 fromSelector, toSelector, data and mimeType (including defaults) are already documented in the schema. The description adds no per-parameter meaning, so the baseline 3 applies.

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 ('Perform an HTML5 drag-and-drop by dispatching the DOM events ... with a real DataTransfer') and explicitly contrasts it with the sibling pointer-based browser_drag, so an agent can pick between them without opening the schema.

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 explicit when-to-use ('works on pages that listen for the standard drag events') and when-not ('pages that check event.isTrusted, or that require genuine OS drag semantics, will still refuse'), plus the named alternative browser_drag and why it fails.

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