shadermaterial_set_param
Set a shader uniform parameter on the ShaderMaterial of a node's material slot in the edited scene (undoable). The node must already have a ShaderMaterial. The value uses the tagged-Variant convention. In-scene and undoable — not gated.
This record as markdown: /tools/breakpoint-mcp/shadermaterial-set-param.md
What shadermaterial_set_param does on Breakpoint
AI agents use shadermaterial_set_param 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 | Node path relative to the scene root |
param | string | Yes | Shader uniform name |
value | object | — | New value (JSON scalar or __type__-tagged Variant) |
Parameters from the server's own tool schema.
Why shadermaterial_set_param is rated Medium
This tool modifies shader parameters on materials in a scene. While marked as 'undoable', it performs a write operation that changes visual rendering properties. It does not create or delete objects (not Destructive), nor execute arbitrary code (not Execute). The impact is reversible and confined to material properties, making it Write rather than more severe.
From the tool's definition Set a shader uniform parameter on the ShaderMaterial of a node's material slot in the edited scene (undoable)
Risk signalsAccepts file system path (path)
Attacks that exploit this kind of access
The rule that runs shadermaterial_set_param 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 shadermaterial_set_param, this is the rule to start with:
shadermaterial_set_param 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 shadermaterial_set_param call is checked against it from then on.
Questions about shadermaterial_set_param
Set a shader uniform parameter on the ShaderMaterial of a node's material slot in the edited scene (undoable). The node must already have a ShaderMaterial. The value uses the tagged-Variant convention. 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.
shadermaterial_set_param accepts 3 parameters: path, param, value. Required: path, param. 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 shadermaterial_set_param: 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.
shadermaterial_set_param 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 shadermaterial_set_param 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 shadermaterial_set_param. 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.
shadermaterial_set_param 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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