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

Annotations already declare destructiveHint=true, readOnlyHint=false, and openWorldHint=true, so the mutation risk is covered structurally. The description adds that the drag happens along screenshot coordinates against visual-only surfaces, which is useful context, but says nothing about permissions, reversibility, or how the drag target is resolved.

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?

A single tightly written sentence with the 'Fallback' qualifier front-loaded so the agent immediately understands the tool's role. No padding, though it is terse enough that it sacrifices needed detail.

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?

An output schema exists, so return values need no explanation, and annotations cover the safety profile. However, for a required-coordinate drag tool with 0% schema coverage, the description omits the one thing an agent must know: how to construct 'path' coordinates.

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 0%, so the description must carry the parameters. It hints that 'path' corresponds to screenshot points, but never explains the array-of-arrays integer format (polyline vs. start/end pair) or what 'job_id' refers to, leaving a real ambiguity for a required 2-param call.

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 (drag) and the resource it interacts with (visual-only controls such as canvas widgets via screenshot points). The 'Fallback' framing distinguishes it conceptually from the element-based siblings, though it never names those siblings directly.

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?

'Fallback' plus 'visual-only controls such as canvas widgets' clearly signals when this tool applies: after DOM-based interaction (click_element, hover_element) cannot reach a target. No explicit exclusions or named alternatives, but the selection context is unambiguous.

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