Overview
The set_selection tool programmatically sets which instances are selected in Roblox Studio’s Explorer window. This allows AI assistants to highlight specific objects for the user, guiding their attention and enabling manual operations on programmatically identified objects.
Use Cases
- Highlight objects for user review
- Guide users to specific instances
- Select objects before manual operations
- Show results of search or filter operations
- Direct user attention to problematic objects
- Enable manual editing of AI-identified objects
- Prepare selection for Studio operations (grouping, etc.)
- Implement “show me” functionality
Parameters
Array of instance paths to select in Studio
Response Structure
Whether the selection was set successfully
Number of instances successfully selected
Array of paths that were selected
Example Response
{
"success": true,
"selectedCount": 3,
"selectedPaths": [
"game.Workspace.Platform_1",
"game.Workspace.Platform_2",
"game.Workspace.Platform_3"
]
}
Usage Examples
Select Single Object
{
"paths": ["game.Workspace.ImportantPart"]
}
Select Multiple Objects
// Select all platforms in a level
const platforms = await mcpClient.callTool('search_objects', {
query: 'Level_01',
searchType: 'name'
});
const paths = platforms.results.map(obj => obj.path);
await mcpClient.callTool('set_selection', {
paths: paths
});
console.log(`Selected ${paths.length} platforms`);
console.log('Please review the selected platforms in Studio.');
Highlight Search Results
// Find and select all red parts
const allParts = await mcpClient.callTool('get_descendants', {
instancePath: 'game.Workspace',
classFilter: 'Part'
});
const redParts = [];
for (const part of allParts.descendants) {
const props = await mcpClient.callTool('get_instance_properties', {
instancePath: part.path
});
if (props.BrickColor === 'Really red') {
redParts.push(part.path);
}
}
await mcpClient.callTool('set_selection', {
paths: redParts
});
console.log(`Found and selected ${redParts.length} red parts`);
Guide User to Errors
// Find problematic objects and show them to user
const problems = await findProblematicObjects();
if (problems.length > 0) {
await mcpClient.callTool('set_selection', {
paths: problems.map(p => p.path)
});
console.log(`Found ${problems.length} issues. Selected problematic objects in Studio.`);
console.log('Please review:');
problems.forEach(p => {
console.log(` - ${p.name}: ${p.issue}`);
});
} else {
console.log('No problems found!');
}
Interactive Object Selection
// Let user choose category, then select those objects
const category = await askUser('Select category (platforms/spawns/checkpoints):');
const objects = await mcpClient.callTool('search_objects', {
query: category,
searchType: 'name'
});
await mcpClient.callTool('set_selection', {
paths: objects.results.map(obj => obj.path)
});
console.log(`Selected all ${category}`);
Select for Manual Grouping
// Select objects that should be grouped, let user group them
const objectsToGroup = await mcpClient.callTool('get_descendants', {
instancePath: 'game.Workspace',
nameFilter: 'Level_01'
});
await mcpClient.callTool('set_selection', {
paths: objectsToGroup.descendants.map(obj => obj.path)
});
console.log('Selected objects for grouping.');
console.log('Press Ctrl+G to group them in Studio.');
Clear Selection
// Clear selection by selecting nothing
await mcpClient.callTool('set_selection', {
paths: []
});
console.log('Selection cleared');
Step-by-Step Guidance
// Guide user through a multi-step process
console.log('Step 1: Review these platforms');
await mcpClient.callTool('set_selection', {
paths: platformPaths
});
await waitForUserConfirmation();
console.log('Step 2: Review these spawns');
await mcpClient.callTool('set_selection', {
paths: spawnPaths
});
await waitForUserConfirmation();
console.log('Step 3: Review these checkpoints');
await mcpClient.callTool('set_selection', {
paths: checkpointPaths
});
console.log('Review complete!');
Select Validation Failures
// Validate objects and select those that failed
const allPlatforms = await mcpClient.callTool('get_descendants', {
instancePath: 'game.Workspace.Obby',
nameFilter: 'Platform'
});
const invalid = [];
for (const platform of allPlatforms.descendants) {
const bounds = await mcpClient.callTool('get_bounding_box', {
instancePath: platform.path
});
if (bounds.size.Y < 1) {
invalid.push(platform.path);
}
}
if (invalid.length > 0) {
await mcpClient.callTool('set_selection', {
paths: invalid
});
console.log(`WARNING: ${invalid.length} platforms are too thin!`);
console.log('Selected invalid platforms for your review.');
}
Select and Prompt for Action
// Select objects and ask user what to do
const oldObjects = await mcpClient.callTool('search_objects', {
query: 'Old',
searchType: 'name'
});
if (oldObjects.results.length > 0) {
await mcpClient.callTool('set_selection', {
paths: oldObjects.results.map(obj => obj.path)
});
console.log(`Found ${oldObjects.results.length} objects with 'Old' in the name.`);
console.log('Selected in Studio for your review.');
const action = await askUser('Delete these? (yes/no)');
if (action === 'yes') {
for (const obj of oldObjects.results) {
await mcpClient.callTool('delete_object', {
instancePath: obj.path
});
}
console.log('Deleted old objects');
}
}
Tips and Best Practices
Use set_selection to guide users to objects that need attention. This is more user-friendly than just listing paths.
The selection will be visible in Studio’s Explorer window. Selected objects will be highlighted.
If any path in the array is invalid, that path will be skipped, but valid paths will still be selected.
Combine with console messages to explain WHY objects are selected. “Selected 5 platforms with invalid sizes” is more helpful than just silently selecting.
Behavior Details
Selection Replacement
set_selection replaces the current selection entirely- Previously selected objects are deselected
- To clear selection, pass an empty array
Invalid Paths
- If a path doesn’t exist, it’s skipped
- Valid paths are still selected
- Response indicates how many were successfully selected
Studio Integration
- Selected objects appear highlighted in Explorer
- Selected objects can be operated on with Studio tools
- Selection persists until changed by user or another call
Multi-Selection
- All paths in the array are selected simultaneously
- Equivalent to Ctrl+clicking multiple objects in Explorer
- Objects can be in different parents or services
Common Patterns
Find-Select-Act
// Find objects
const found = await findObjects(criteria);
// Select for user review
await mcpClient.callTool('set_selection', {
paths: found.map(obj => obj.path)
});
// Ask user for action
const action = await askUser('What to do with selected objects?');
// Perform action
await performAction(action, found);
Validation and Highlight
// Validate, select failures
const failures = await validateObjects();
if (failures.length > 0) {
await mcpClient.callTool('set_selection', { paths: failures });
console.log('Selected invalid objects for review');
}
Progressive Selection
// Select objects one group at a time
for (const group of objectGroups) {
await mcpClient.callTool('set_selection', {
paths: group.paths
});
console.log(`Reviewing ${group.name}...`);
await waitForUserConfirmation();
}
Clear and Select
// Ensure clean selection
await mcpClient.callTool('set_selection', { paths: [] }); // Clear
await mcpClient.callTool('set_selection', { paths: newPaths }); // Select
Common Issues
Issue: Objects not appearing selected
- Verify paths are correct and objects exist
- Check Studio Explorer window (selection may not be visible in viewport)
- Ensure MCP bridge is connected
Issue: Selection includes unexpected objects
- set_selection selects ONLY the provided paths
- Double-check the paths array
- Verify search/filter logic that generated the paths
Issue: Selection cleared immediately
- User may have clicked elsewhere in Studio
- Another MCP operation may have cleared selection
- Selection is temporary and can be changed by user
Issue: Can’t select certain objects
- Some system objects may not be selectable
- Objects in certain services may be restricted
- Verify the object exists and is not hidden
