---
name: assets-modify
description: Modify an asset file in the project. Use 'assets-get-data' first to inspect the asset structure before modifying. Not allowed to modify asset files in the 'Packages/' folder — modify them in 'Assets/'. Three modification surfaces are available (content, pathPatches, jsonPatch) — see the skill body for details.
---

# Assets / Modify

## Three modification surfaces

Use whichever fits the task:

1. `content` — full `SerializedMember` override (legacy, backwards compatible).
2. `pathPatches` — list of `{path, value}` pairs routed through `Reflector.TryModifyAt`.
3. `jsonPatch` — JSON Merge Patch routed through `Reflector.TryPatch`.

When more than one is supplied they run in this order: `jsonPatch` → `pathPatches` → `content`. At least one is required.

## Path syntax

`fieldName`, `nested/field`, `arrayField/[i]`, `dictField/[key]`. Leading `#/` is stripped.

## How to Call

```bash
unity-mcp-cli run-tool assets-modify --input '{
  "assetRef": "string_value",
  "content": "string_value",
  "pathPatches": "string_value",
  "jsonPatch": "string_value"
}'
```

> For complex input (multi-line strings, code), save the JSON to a file and use:
> ```bash
> unity-mcp-cli run-tool assets-modify --input-file args.json
> ```
>
> Or pipe via stdin (recommended):
> ```bash
> unity-mcp-cli run-tool assets-modify --input-file - <<'EOF'
> {"param": "value"}
> EOF
> ```


### Troubleshooting

If `unity-mcp-cli` is not found, either install it globally (`npm install -g unity-mcp-cli`) or use `npx unity-mcp-cli` instead.
Read the /unity-initial-setup skill for detailed installation instructions.

## Input

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `assetRef` | `any` | Yes | Reference to UnityEngine.Object asset instance. It could be Material, ScriptableObject, Prefab, and any other Asset. Anything located in the Assets and Packages folders. |
| `content` | `any` | No | Optional. The asset content. It overrides the existing asset content (legacy path). |
| `pathPatches` | `any` | No | Optional. List of path-scoped patches routed through Reflector.TryModifyAt. |
| `jsonPatch` | `any` | No | Optional. JSON Merge Patch (RFC 7396, extended with [i]/[key] keys) routed through Reflector.TryPatch. |

### Input JSON Schema

```json
{
  "type": "object",
  "properties": {
    "assetRef": {
      "$ref": "#/$defs/AIGD.AssetObjectRef"
    },
    "content": {
      "$ref": "#/$defs/com.IvanMurzak.ReflectorNet.Model.SerializedMember"
    },
    "pathPatches": {
      "$ref": "#/$defs/System.Collections.Generic.List(AIGD.PathPatch)"
    },
    "jsonPatch": {
      "anyOf": [
        {
          "type": "string"
        },
        {
          "type": "object",
          "additionalProperties": true
        }
      ]
    }
  },
  "$defs": {
    "System.Type": {
      "type": "string"
    },
    "AIGD.AssetObjectRef": {
      "type": "object",
      "properties": {
        "instanceID": {
          "type": "integer",
          "description": "instanceID of the UnityEngine.Object. If this is '0' and 'assetPath' and 'assetGuid' is not provided, empty or null, then it will be used as 'null'."
        },
        "assetType": {
          "$ref": "#/$defs/System.Type",
          "description": "Type of the asset."
        },
        "assetPath": {
          "type": "string",
          "description": "Path to the asset within the project. Starts with 'Assets/'"
        },
        "assetGuid": {
          "type": "string",
          "description": "Unique identifier for the asset."
        }
      },
      "required": [
        "instanceID"
      ],
      "description": "Reference to UnityEngine.Object asset instance. It could be Material, ScriptableObject, Prefab, and any other Asset. Anything located in the Assets and Packages folders."
    },
    "com.IvanMurzak.ReflectorNet.Model.SerializedMemberList": {
      "type": "array",
      "items": {
        "$ref": "#/$defs/com.IvanMurzak.ReflectorNet.Model.SerializedMember"
      }
    },
    "com.IvanMurzak.ReflectorNet.Model.SerializedMember": {
      "type": "object",
      "properties": {
        "typeName": {
          "type": "string",
          "description": "Full type name. Eg: 'System.String', 'System.Int32', 'UnityEngine.Vector3', etc."
        },
        "name": {
          "type": "string",
          "description": "Object name."
        },
        "value": {
          "description": "Value of the object, serialized as a non stringified JSON element. Can be null if the value is not set. Can be default value if the value is an empty object or array json."
        },
        "fields": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/com.IvanMurzak.ReflectorNet.Model.SerializedMember",
            "description": "Nested field value."
          },
          "description": "Fields of the object, serialized as a list of 'SerializedMember'."
        },
        "props": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/com.IvanMurzak.ReflectorNet.Model.SerializedMember",
            "description": "Nested property value."
          },
          "description": "Properties of the object, serialized as a list of 'SerializedMember'."
        }
      },
      "required": [
        "typeName"
      ],
      "additionalProperties": false
    },
    "AIGD.PathPatch": {
      "type": "object",
      "properties": {
        "Path": {
          "type": "string",
          "description": "Slash-delimited path to the target field/element/entry. Plain segment navigates a field or property (e.g. 'admin' or 'admin/name'). Use '[i]' for array/list index (e.g. 'planets/[0]/orbitRadius'). Use '[key]' for dictionary entry (e.g. 'config/[timeout]'). A leading '#/' is stripped automatically. Required."
        },
        "Value": {
          "$ref": "#/$defs/com.IvanMurzak.ReflectorNet.Model.SerializedMember",
          "description": "The new value to write at the path. Use the standard SerializedMember envelope: 'typeName' + 'value' for primitives, or nested 'fields'/'props' for complex types. Required — omitting it overwrites the target with a default empty SerializedMember."
        }
      }
    },
    "System.Collections.Generic.List(AIGD.PathPatch)": {
      "type": "array",
      "items": {
        "$ref": "#/$defs/AIGD.PathPatch"
      }
    }
  },
  "required": [
    "assetRef"
  ]
}
```

## Output

### Output JSON Schema

```json
{
  "type": "object",
  "properties": {
    "result": {
      "$ref": "#/$defs/System.String-1"
    }
  },
  "$defs": {
    "System.String-1": {
      "type": "array",
      "items": {
        "type": "string"
      }
    }
  },
  "required": [
    "result"
  ]
}
```