left_click_drag

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

With no annotations, the description carries the full behavioral burden, and it does disclose one important trait: the frontmost application must be in the session allowlist or the call fails and does nothing. That failure semantics is genuinely useful, but it says nothing about whether the operation blocks, timing/interpolation of the move, or permission prompts.

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?

Two short sentences, no filler, with the action sequence front-loaded and the failure constraint second. It is tight, though the first sentence is terse enough to feel slightly clipped.

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 two-parameter input tool with no output schema and no annotations, the description plus the detailed schema covers the essentials: what it does, the endpoint semantics, and the allowlist failure mode. Only the blocking/timing behavior and the atomic-sibling tradeoff are absent.

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% and both coordinate parameters are richly documented in the schema (end point, optional start point defaulting to current cursor, pixel origin, scaling handled). The description adds no parameter-level information beyond that, so the baseline of 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?

The description spells out the exact action sequence (press, move to target, release), which unambiguously identifies a drag operation and distinguishes it from the atomic siblings left_mouse_down, mouse_move, and left_mouse_up. It never uses the word 'drag' or names the resource explicitly, but the sequence is specific enough to select correctly.

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?

There is no guidance on when to prefer this composite drag over manually chaining left_mouse_down / mouse_move / left_mouse_up, nor any mention of computer_batch for multi-step interactions. The allowlist statement is a precondition/error condition rather than usage guidance.

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