manage_components set_property cannot target specific component when multiple of same type exist

[dsarno]

Problem

When a GameObject has multiple components of the same type (e.g., three instances of a custom FlowReductionEventDriver MonoBehaviour), manage_components with action: set_property always targets the first matching component. There is no way to specify which component instance to modify.

Steps to Reproduce

1. Add 3 instances of the same component type to a GameObject
2. Use manage_components set_property with component_type to set a property
3. Only the first component instance is ever modified — the second and third are unreachable

Expected Behavior

Ability to target a specific component instance, e.g. by:

• Component instance ID (already returned by the add action in componentInstanceID)
• Component index on the GameObject
• Some other disambiguator

Workaround

Currently have to ask the user to wire the remaining components manually in the Unity Inspector, which defeats the purpose of the MCP tooling.

Context

This comes up when a pattern calls for multiple instances of a driver component on the same GameObject, each configured with different event references and targets (e.g., one per vessel path for bloodflow reduction).

[zzhhdaaa]

Reproduced against the repo test project (TestProjects/UnityMCPTests) on Unity 6000.3.9f1, using the local package from this checkout.

I used a minimal repro harness that creates one GameObject with three Issue1014MultiInstanceComponent instances, then calls ManageComponents.HandleCommand() with:

{
  "action": "set_property",
  "target": "Issue1014ReproGO",
  "search_method": "by_name",
  "component_type": "Issue1014MultiInstanceComponent",
  "property": "slot",
  "value": 42
}

Observed output from the headless repro run:

[Issue1014Repro] Before set_property: first(id=-1308, slot=0), second(id=-1310, slot=0), third(id=-1312, slot=0)
[Issue1014Repro] set_property result: {
  "success": true,
  "message": "Properties set on component 'Issue1014MultiInstanceComponent' on 'Issue1014ReproGO'.",
  "data": {
    "instanceID": -1304
  }
}
[Issue1014Repro] After set_property: first(id=-1308, slot=42), second(id=-1310, slot=0), third(id=-1312, slot=0)

So this issue is confirmed: set_property reports success, but with multiple same-type components on the target GameObject it only mutates the first matching instance.

[Scriptwonder]

Hi David, push a component_index feature into the beta branch. Right now, it can use the component_index to select which component to work. Let me know if this works!

[dsarno]

@Scriptwonder It works! Thanks for fixing, and for all your other great work lately!