runtime_assert_scene_structure
Assert the LIVE SceneTree matches structural expectations (read-only). Each entry asserts a node exists at a path (and, if given, is of a class via is_class); set absent:true to assert it is NOT present.
This record as markdown: /tools/breakpoint-mcp/runtime-assert-scene-structure.md
What runtime_assert_scene_structure does on Breakpoint
AI agents use runtime_assert_scene_structure to create or update resources in Breakpoint, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Breakpoint environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
peer | string | — | Headless peer id from runtime_spawn_peers; omit for the default running game. |
expect | array | Yes | List of node expectations: {path, type?, absent?}. |
Parameters from the server's own tool schema.
Why runtime_assert_scene_structure is rated Medium
An AI agent can call runtime_assert_scene_structure faster than any human can review: one bad instruction and it creates or modifies resources in Breakpoint by the hundred, each call as confident as the last.
Risk signalsAccepts file system path (expect[].path)
Attacks that exploit this kind of access
The rule that runs runtime_assert_scene_structure safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Breakpoint, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For runtime_assert_scene_structure, this is the rule to start with:
runtime_assert_scene_structure 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Breakpoint, apply this rule, and every runtime_assert_scene_structure call is checked against it from then on.
Questions about runtime_assert_scene_structure
Assert the LIVE SceneTree matches structural expectations (read-only). Each entry asserts a node exists at a path (and, if given, is of a class via is_class); set absent:true to assert it is NOT present. It is categorised as a Write tool in the Breakpoint MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
runtime_assert_scene_structure accepts 2 parameters: peer, expect. Required: expect. The full parameter table on this page comes from the server's own tool schema.
Register the Breakpoint MCP server in PolicyLayer and add a rule for runtime_assert_scene_structure: 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 Breakpoint. Nothing to install.
runtime_assert_scene_structure 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 runtime_assert_scene_structure 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 runtime_assert_scene_structure. 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.
runtime_assert_scene_structure is provided by the Breakpoint MCP server (breakpoint-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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