CoplayDev/unity-mcp · error · Exception

edgeIndices or edges parameter is required.

Error message

edgeIndices or edges parameter is required.

What it means

Thrown by ResolveEdges when neither 'edgeIndices'/'edge_indices' nor 'edges' parameter is provided. The edge resolution logic requires at least one of these: an array of integer indices into the unique edge list, or an array of {a, b} vertex-pair objects.

Source

Thrown at MCPForUnity/Editor/Tools/ProBuilder/ManageProBuilder.cs:524

                    int b = pair["b"]?.Value<int>() ?? 0;
                    edgeList.Add(CreateEdge(a, b));
                }
            }
            else if (edgeIndicesToken != null)
            {
                // Edge specification by index into unique edges
                var allEdges = CollectUniqueEdges(pbMesh);
                var edgeIndices = edgeIndicesToken.ToObject<int[]>();
                foreach (int idx in edgeIndices)
                {
                    if (idx < 0 || idx >= allEdges.Count)
                        throw new Exception($"Edge index {idx} out of range (0-{allEdges.Count - 1}).");
                    edgeList.Add(allEdges[idx]);
                }
            }
            else
            {
                throw new Exception("edgeIndices or edges parameter is required.");
            }

            count = edgeList.Count;
            var edgeArray = Array.CreateInstance(_edgeType, edgeList.Count);
            for (int i = 0; i < edgeList.Count; i++)
                edgeArray.SetValue(edgeList[i], i);
            return edgeArray;
        }

        /// <summary>
        /// Create a typed List&lt;Edge&gt; from an Edge[] array for APIs that require IList&lt;Edge&gt;.
        /// </summary>
        private static System.Collections.IList ToTypedEdgeList(Array edgeArray)
        {
            var edgeListType = typeof(List<>).MakeGenericType(_edgeType);
            var typedList = Activator.CreateInstance(edgeListType) as System.Collections.IList;
            foreach (var e in edgeArray)
                typedList.Add(e);

View on GitHub (pinned to c21bf496bc)

Solutions

1. Provide 'edges' as an array of vertex-pair objects: [{"a": 0, "b": 1}, ...].
2. Alternatively provide 'edgeIndices' as an array of integers referencing unique edge indices.
3. If you need all edges, enumerate them first and build the edgeIndices array from the full set.
4. Double-check parameter names: the tool accepts 'edges' or 'edgeIndices'/'edge_indices'.

Example fix

// before
params = {"target": "MyShape", "action": "bevel_edges"}
// after
params = {"target": "MyShape", "action": "bevel_edges", "edges": [{"a": 0, "b": 1}, {"a": 2, "b": 3}]}

# Ensure at least one edge specification is present before calling
def has_edge_spec(params):
    return 'edges' in params or 'edgeIndices' in params or 'edge_indices' in params

if not has_edge_spec(params):
    raise ValueError('Provide edges [{a,b},...] or edgeIndices [int,...]')

try
{
    var edges = ResolveEdges(pbMesh, props, out int count);
}
catch (Exception ex) when (ex.Message == "edgeIndices or edges parameter is required.")
{
    return new ErrorResponse("Specify edges as vertex pairs or edgeIndices.");
}

When it happens

Trigger: Calling an edge-based ProBuilder operation (e.g. bevel_edges, extrude_edges) without specifying which edges to operate on. The tool has no default 'all edges' behavior for edge operations.

Common situations: AI omits edge parameters assuming the tool will operate on all edges; parameter naming convention mismatch (using 'edge_list' or 'selectedEdges' instead of 'edges' or 'edgeIndices'); empty object passed instead of an array.

Related errors

• Edge index {idx} out of range (0-{allEdges.Count - 1}).
• Face index {indices[i]} out of range (0-{facesList.Count - 1
• Unknown shape type '{shapeTypeStr}'. Valid types: {validType
• Color array must have 3 or 4 elements.
• Port must be positive.

AI-assisted analysis of CoplayDev/unity-mcp@c21bf496bc (2026-08-13). Data as JSON: /api/errors/3b077b188cb0b962. Report an issue: GitHub.