joint_set_bodies
Set node_a and/or node_b on an existing Joint2D/3D in the edited scene (undoable) — the NodePaths of the two bodies the joint connects, relative to the joint node. In-scene and undoable — not gated.
This record as markdown: /tools/breakpoint-mcp/joint-set-bodies.md
What joint_set_bodies does on Breakpoint
AI agents use joint_set_bodies 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 |
|---|---|---|---|
path | string | Yes | Joint2D/3D node path relative to the scene root |
node_a | string | — | NodePath (relative to the joint) of the first body |
node_b | string | — | NodePath (relative to the joint) of the second body |
Parameters from the server's own tool schema.
Why joint_set_bodies is rated Medium
This tool modifies existing joint node configurations by changing which bodies the joint connects. While the change is undoable (making it reversible), it alters scene structure and could affect physics behavior or rendering if misused by an agent without understanding the scene context. The medium severity reflects the reversible nature (undoable) but acknowledges potential for unintended scene corruption.
From the tool's definition Tool description explicitly states it 'Set[s] node_a and/or node_b on an existing Joint2D/3D' and is 'undoable', indicating reversible modification of scene properties.
Risk signalsAccepts file system path (path)
Attacks that exploit this kind of access
The rule that runs joint_set_bodies 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 joint_set_bodies, this is the rule to start with:
joint_set_bodies 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 joint_set_bodies call is checked against it from then on.
Questions about joint_set_bodies
Set node_a and/or node_b on an existing Joint2D/3D in the edited scene (undoable) — the NodePaths of the two bodies the joint connects, relative to the joint node. In-scene and undoable — not gated. 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.
joint_set_bodies accepts 3 parameters: path, node_a, node_b. Required: path. 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 joint_set_bodies: 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.
joint_set_bodies 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 joint_set_bodies 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 joint_set_bodies. 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.
joint_set_bodies 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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