Sets a QML property such as checked, value, text, or currentIndex on a UI element using its ref; use when direct property changes are needed instead of simulated input.
Set a QML property on an element (e.g. checked, value, text, currentIndex). Bypasses input handlers; prefer ui_click when possible.
| Name | Required | Description | Default |
|---|---|---|---|
| ref | Yes | Element ref from the latest ui_tree or dialogs result. | |
| name | Yes | ||
| value | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It does disclose one genuinely important trait — that this mutates state without dispatching input events — which an agent could not infer from the schema. However, it says nothing about persistence, whether bindings/signals fire, required element visibility, or failure behavior, leaving the mutation profile largely undisclosed.
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 compact sentences, zero filler. The core operation and its examples come first, and the usage caveat follows in the strongest possible position for a reader scanning the tail.
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 3-required-parameter mutation tool with no annotations and no output schema, the description covers purpose, the key behavioral caveat, and an alternative. It still omits value-type expectations, error/return behavior, and how to obtain a valid `ref` beyond the schema hint, so an agent may need to probe to call it correctly.
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 only 33%: `ref` is documented in the schema, while `name` and `value` are bare. The description partially compensates by giving example property names, which clarifies `name`, but `value` is an untyped `{}` with no explanation of how its type must match the target property — a real gap.
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 names a specific verb and resource ("Set a QML property on an element") and enumerates concrete example properties (checked, value, text, currentIndex), so an agent knows exactly what operation it performs. It doesn't explicitly contrast with sibling setters, but the examples pin down the domain well enough to distinguish it from ui_click/ui_type.
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 names an alternative and a selection rule: "prefer ui_click when possible," plus the reason (this bypasses input handlers). It stops short of stating hard exclusions or prerequisites (e.g. element must be present in the latest ui_tree), so it's clear guidance rather than complete guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.