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

With no annotations provided, the description carries the full burden of behavioral disclosure. It covers the HID direct input path, single-contact constraint, hold timing purpose, and the 'no HID available' error on iOS 17.x/no-tunnel. These are valuable traits not inferable from the 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 dense but well-organized: behavior first, contrast with sibling second, use cases third, coordinate guidance fourth, then constraints and failure mode. Every sentence earns its place without filler or redundant restating.

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 gesture tool with a fully documented schema and no output schema, this description covers the essential context: gesture sequence, timing rationale, coordinate space, single-contact constraint, and known error case. Nothing needed to invoke it correctly is missing.

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 the baseline is 3. The description adds behavioral meaning to holdStartMs and holdEndMs beyond their schema descriptions, and reinforces the norm=true coordinate formula, helping the agent compute values correctly even though the schema already mentions it.

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 opens with a specific verb and resource: 'Drag-and-drop via the direct input path'. It then spells out the full gesture sequence (press-and-hold, move, release), clearly distinguishing it from ios_swipe_hid by noting it holds at both ends. An agent can unambiguously tell this tool from its closest sibling.

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?

It explicitly contrasts with ios_swipe_hid, explaining why a bare swipe often fails to grab or drop, and gives concrete use cases: reordering, sliders, and canvas drag-and-drop. This is clear when-to-use guidance with a named alternative and failure mode context.

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