Constant GLOBAL_MEMORY_DIFF_TOOL 

pub(crate) const GLOBAL_MEMORY_DIFF_TOOL: &str = r#"{
  "name": "GlobalMemoryDiff",
  "description": "Show a line-based diff between two recorded versions of a Global Memory entry (workspace-wide shared state, not your own native memory — use MemoryDiff for that). Get version ids from GlobalMemoryHistory.",
  "inputSchema": {
    "type": "object",
    "properties": {
      "id": { "type": "string", "description": "The Global Memory entry id both versions belong to (from GlobalMemoryList)" },
      "from_version_id": { "type": "string", "description": "The earlier version id (from GlobalMemoryHistory)" },
      "to_version_id":   { "type": "string", "description": "The later version id (from GlobalMemoryHistory)" }
    },
    "required": ["id", "from_version_id", "to_version_id"]
  }
}"#;