Selects a visible enabled combobox item by value when supported, then compares selected-value readback. Older viewers need path-targeted ui_press_key.
Select a visible enabled combobox item by actual value, when supported by the viewer, and compare selected-value readback. Older viewers require path-targeted ui_press_key with readback.
| Name | Required | Description | Default |
|---|---|---|---|
| path | Yes | ||
| value | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare destructiveHint=true, openWorldHint=true and readOnlyHint=false, so the agent is warned this is a mutating, side-effect-capable operation. The description adds the precondition that the item must be visible and enabled and mentions a selected-value readback step, but says nothing about what side effects the selection may trigger or what happens on failure.
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 tightly packed sentences with the core action and precondition front-loaded and the fallback follow-up second. No filler text.
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?
With no output schema, no annotation detail on returns, and 0% schema coverage, the description supplies the precondition, the value semantics, and the legacy fallback, which is close to sufficient. It stops short of covering failure modes or the readback comparison result the caller should expect.
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% for both required parameters, so the description must carry meaning. It clarifies that 'value' is the actual value (not display label) and that the target is path-based, which is genuinely useful, but it does not explain path syntax or accepted value types for the anyOf value parameter.
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 (Select) and a specific resource (a visible enabled combobox item, identified by actual value), and the selector semantics are precise enough to distinguish it from generic ui_click. It even names the sibling it is not (path-targeted ui_press_key) for older viewers.
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?
Gives a real usage condition ('when supported by the viewer') plus an explicit fallback path for older viewers ('ui_press_key with readback'), which is stronger than most siblings. It does not, however, say when to prefer this over ui_set_text or ui_get_value for the same control.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.