⚠️ WEB PROJECTS ONLY - NOT FOR DESKTOP! Add a custom A-Frame component for web-based 8th Wall projects (requires index.html with A-Frame). Desktop projects (.expanse.json) use Three.js directly - use desktop_add_threejs_script instead!
AI agents use desktop_add_custom_component to create or update resources in 8th Wall MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your 8th Wall MCP Server environment.
This tool creates or modifies A-Frame components in web-based 8th Wall projects. While it does not delete data (not Destructive) or execute arbitrary code at runtime (not Execute in the sense of running shell commands), it does write/inject code into project files that will be executed when the AR experience runs. This is reversible (components can be removed or modified), making it Write rather than Execute.
From the tool's definition Tool description uses 'Add' and mentions 'Add a custom A-Frame component', which creates/modifies code artifacts within a web project. The warning about project types and the reference to adding components to index.html clarifies it writes to project files.
Documented attack patterns abuse exactly the kind of access desktop_add_custom_component gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and 8th Wall MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for desktop_add_custom_component:
{
"version": "1",
"default": "deny",
"tools": {
"desktop_add_custom_component": {
"limits": [
{
"counter": "desktop_add_custom_component_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}desktop_add_custom_component stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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⚠️ WEB PROJECTS ONLY - NOT FOR DESKTOP! Add a custom A-Frame component for web-based 8th Wall projects (requires index.html with A-Frame). Desktop projects (.expanse.json) use Three.js directly - use desktop_add_threejs_script instead!. It is categorised as a Write tool in the 8th Wall MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the 8th Wall MCP Server MCP server in PolicyLayer and add a rule for desktop_add_custom_component: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches 8th Wall MCP Server. Nothing to install.
desktop_add_custom_component is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the desktop_add_custom_component rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for desktop_add_custom_component. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
desktop_add_custom_component is provided by the 8th Wall MCP Server MCP server (superdwayne/8thwallmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from 8th Wall MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
64 8th Wall MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.