set_mobile_position

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

With no annotations provided, the description carries the full burden. It discloses that the tool operates on a 320-wide phone canvas, creates a second layouts entry, and explains how mobileFormat overrides are stamped. This adds meaningful behavioral context beyond what a simple 'set position' would imply. It does not explicitly state whether existing position is overwritten, but the term 'Place' inherently suggests setting coordinates. The detail about the canvas width is especially valuable for coordinate calculations.

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 sentences with no fluff. The first sentence front-loads the primary action and scope, while the second efficiently explains the only complex parameter (mobileFormat). Every phrase earns its place, and the structure is easy to parse.

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?

Given the tool has 8 parameters and no output schema or annotations, the description covers the essential context: canvas dimensions, the separate mobile layout entry, and the optional formatting override. It does not explain prerequisites (e.g., visual must exist) or return behavior, but these are not critical for a placement tool. The reference to 'set_visual_format-shaped JSON' assumes knowledge of another tool, but the example mitigates this. Overall, it is fairly complete for its complexity.

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 only 13%, so the description must compensate. It does provide substantial meaning for mobileFormat (a set_visual_format-shaped JSON of mobile-specific overrides with an example), and the mention of '320-wide phone canvas' gives context for x/y/width/height values. However, it does not explain pageName, visualName, or reportSessionId beyond their names, which are likely standard. It partially compensates for low coverage but does not fully describe all parameters.

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 clearly states the tool's function: 'Place one visual on the phone (mobile) layout at x,y,width,height on the 320-wide phone canvas'. This specific verb+resource scope distinguishes it from siblings like set_visual_position (which likely targets the desktop layout) and auto_mobile_layout (which automates placement). Mentioning 'a second layouts entry' further clarifies its unique role.

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 phrase 'Use for precise mobile control' gives clear context for when to use this tool, implying that other tools (e.g., auto_mobile_layout) are suited for automatic placement. It does not explicitly list alternatives or exclusions, but the contrast with automation is evident. This is clear enough for an AI agent to choose it over siblings for manual mobile positioning.

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