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

With no annotations, the description carries the full burden of behavioral disclosure. It discloses that this is a desktop-browser-only synthetic drag (not a device gesture), gives concrete use cases (reorderable lists, kanban columns, file drop targets), and clarifies the platform limitation. While it doesn't discuss side effects or return behavior, the description provides more behavioral context than the bare schema alone.

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 two tightly packed sentences with no filler. The core purpose is front-loaded, followed by a concise exclusion and routing rule. Every clause adds useful information, and the structure makes it easy to scan quickly.

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 action tool with three required params, no output schema, and full schema coverage, the description is complete: it states what it does, the platform scope, and the correct alternatives. The only minor gap is not defining 'DESKTOP grid browser,' but that appears to be a known product concept, and the pageId reference grounds it in the web automation workflow.

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?

All three parameters (to, from, pageId) are described in the schema, and the schema coverage is 100%, so the description does not need to compensate. The description adds minor context by listing drag use cases that inform what selectors might target, but it does not meaningfully extend the schema's parameter definitions.

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 uses a specific verb ('Drag') with a clear resource ('one element onto another') and context ('in the DESKTOP grid browser by pageId'). It also explicitly distinguishes itself from device-level drag tools and notes that no webpage_drag sibling exists, making the tool's unique role unambiguous.

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 explicitly states when NOT to use this tool ('NOT a device') and provides exact alternatives for real devices: device_swipe / device_drag_drop (Android) or ios_drag_drop (iOS), by udid. This is a clear routing rule that leaves no ambiguity about tool selection.

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