signal_add_user_signal
Declare a new user signal on a node (undoable). Optional typed arguments. Errors if the signal already exists.
This record as markdown: /tools/breakpoint-mcp/signal-add-user-signal.md
What signal_add_user_signal does on Breakpoint
AI agents use signal_add_user_signal 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 |
|---|---|---|---|
args | array | — | Signal parameters (name + Variant type int) |
path | string | Yes | Node path relative to the scene root |
signal | string | Yes | New signal name |
Parameters from the server's own tool schema.
Why signal_add_user_signal is rated Medium
This tool creates/declares a new signal on a node, which is a modification to the node's structure and metadata. While it changes state, it is explicitly marked as undoable (reversible), and does not delete, execute arbitrary code, move money, or query data. This places it firmly in Write category (create operation).
From the tool's definition Tool description states it 'Declare a new user signal on a node (undoable)' - a create operation that modifies the node's signal definitions. The (undoable) note confirms reversibility, distinguishing this from Destructive actions.
Risk signalsAccepts file system path (path)
Attacks that exploit this kind of access
The rule that runs signal_add_user_signal 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 signal_add_user_signal, this is the rule to start with:
signal_add_user_signal 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 signal_add_user_signal call is checked against it from then on.
Questions about signal_add_user_signal
Declare a new user signal on a node (undoable). Optional typed arguments. Errors if the signal already exists. 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.
signal_add_user_signal accepts 3 parameters: args, path, signal. Required: path, signal. 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 signal_add_user_signal: 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.
signal_add_user_signal 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 signal_add_user_signal 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 signal_add_user_signal. 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.
signal_add_user_signal 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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