# add_niagara_event_handler

A write tool on the Unreal-MCP MCP server.

Agent View of the PolicyLayer registry record for `add_niagara_event_handler`. HTML page: https://policylayer.com/tools/aadeshrao123-unreal-mcp/add-niagara-event-handler

## Facts

- Tool: `add_niagara_event_handler`
- Server: Unreal-MCP (`aadeshrao123/unreal-mcp`) — https://policylayer.com/tools/aadeshrao123-unreal-mcp.md
- Homepage: https://github.com/aadeshrao123/Unreal-MCP
- Risk category: Write (Medium risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "add_niagara_event_handler",
    "arguments": {}
  }
}
```

## Why add_niagara_event_handler is rated Medium

This tool creates new event handlers within Niagara particle systems, which modifies the VFX configuration reversibly. While it does not delete data (Destructive), execute arbitrary code (Execute), or move money (Financial), it creates/modifies engine assets. The 'add_' prefix combined with Niagara VFX context indicates a Write operation.

From the tool's own definition: "Tool name 'add_niagara_event_handler' indicates creation of event handlers in Unreal Engine's Niagara VFX system."

## Use case

AI agents use add_niagara_event_handler to create or update resources in Unreal-MCP, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Unreal-MCP environment.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Unreal-MCP:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "add_niagara_event_handler": {
      "limits": [
        {
          "counter": "add_niagara_event_handler_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Unreal-MCP (285)

- `cleanup_material_function` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/cleanup-material-function.md
- `cleanup_material_graph` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/cleanup-material-graph.md
- `clear_niagara_module_input` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/clear-niagara-module-input.md
- `delete_actor` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/delete-actor.md
- `delete_asset` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/delete-asset.md
- `delete_blueprint_function` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/delete-blueprint-function.md
- `delete_blueprint_node` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/delete-blueprint-node.md
- `delete_data_table_row` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/delete-data-table-row.md
- `delete_material_expression` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/delete-material-expression.md
- `delete_niagara_graph_node` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/delete-niagara-graph-node.md
- `delete_niagara_scratch_pad_module` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/delete-niagara-scratch-pad-module.md
- `delete_niagara_system` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/delete-niagara-system.md
- `remove_input_action_modifier` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-input-action-modifier.md
- `remove_input_action_trigger` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-input-action-trigger.md
- `remove_key_mapping` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-key-mapping.md
- `remove_mapping_modifier` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-mapping-modifier.md
- `remove_mapping_trigger` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-mapping-trigger.md
- `remove_mass_config_trait` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-mass-config-trait.md
- `remove_niagara_custom_hlsl_pin` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-niagara-custom-hlsl-pin.md
- `remove_niagara_emitter` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-niagara-emitter.md
- `remove_niagara_module` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-niagara-module.md
- `remove_niagara_node_pin` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-niagara-node-pin.md
- `remove_niagara_renderer` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-niagara-renderer.md
- `remove_niagara_script_parameter` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-niagara-script-parameter.md
- `remove_niagara_user_parameter` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-niagara-user-parameter.md
- `remove_statetree_binding` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-statetree-binding.md
- `remove_statetree_node` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-statetree-node.md
- `remove_statetree_parameter` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-statetree-parameter.md
- `remove_statetree_state` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-statetree-state.md
- `remove_statetree_transition` — Destructive — https://policylayer.com/tools/aadeshrao123-unreal-mcp/remove-statetree-transition.md
- …and 255 more: https://policylayer.com/tools/aadeshrao123-unreal-mcp.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=aadeshrao123-unreal-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/aadeshrao123-unreal-mcp