Unity-MCP assets-modify

Modify asset file in the project. Use 'assets-get-data' tool first to inspect the asset structure before modifying. Not allowed to modify asset file in 'Packages/' folder. Please modify it in 'Assets/' folder.

install

source · Clone the upstream repo

git clone https://github.com/IvanMurzak/Unity-MCP

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/IvanMurzak/Unity-MCP "$T" && mkdir -p ~/.claude/skills && cp -r "$T/Unity-MCP-Plugin/.claude/skills/assets-modify" ~/.claude/skills/ivanmurzak-unity-mcp-assets-modify && rm -rf "$T"

manifest: Unity-MCP-Plugin/.claude/skills/assets-modify/SKILL.md

source content

Assets / Modify

How to Call

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

For complex input (multi-line strings, code), save the JSON to a file and use:

unity-mcp-cli run-tool assets-modify --input-file args.json

Or pipe via stdin (recommended):

unity-mcp-cli run-tool assets-modify --input-file - <<'EOF'
{"param": "value"}
EOF

Troubleshooting

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`	Yes	The asset content. It overrides the existing asset content.

Input JSON Schema

{
  "type": "object",
  "properties": {
    "assetRef": {
      "$ref": "#/$defs/com.IvanMurzak.Unity.MCP.Runtime.Data.AssetObjectRef"
    },
    "content": {
      "$ref": "#/$defs/com.IvanMurzak.ReflectorNet.Model.SerializedMember"
    }
  },
  "$defs": {
    "System.Type": {
      "type": "string"
    },
    "com.IvanMurzak.Unity.MCP.Runtime.Data.AssetObjectRef": {
      "type": "object",
      "properties": {
        "instanceID": {
          "type": "integer",
          "description": "instanceID of the UnityEngine.Object. If this is '0' and 'assetPath' and 'assetGuid' is not provided, empty or null, then it will be used as 'null'."
        },
        "assetType": {
          "$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
    }
  },
  "required": [
    "assetRef",
    "content"
  ]
}

Output

Output JSON Schema

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