batch_set_expression
Set the same expression on a property across multiple layers.
This record as markdown: /tools/synthetic-ai-ae-mcp/batch-set-expression.md
What batch_set_expression does on Ae
AI agents use batch_set_expression to create or update resources in Ae, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Ae environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
save | boolean | — | |
compName | string | Yes | |
timeoutMs | number | — | |
expression | string | Yes | Expression string to set. Empty string removes expression. |
layerNames | array | — | |
projectPath | string | — | |
propertyPath | array | Yes | Property path (match names). |
Parameters from the server's own tool schema.
Why batch_set_expression is rated Medium
An AI agent can call batch_set_expression faster than any human can review: one bad instruction and it creates or modifies resources in Ae by the hundred, each call as confident as the last.
Risk signalsAccepts freeform code/query input (expression) · Bulk/mass operation — affects multiple targets
Attacks that exploit this kind of access
The rule that runs batch_set_expression safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Ae, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For batch_set_expression, this is the rule to start with:
batch_set_expression 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 Ae, apply this rule, and every batch_set_expression call is checked against it from then on.
Questions about batch_set_expression
Set the same expression on a property across multiple layers. It is categorised as a Write tool in the Ae MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
batch_set_expression accepts 7 parameters: save, compName, timeoutMs, expression, layerNames, projectPath, propertyPath. Required: compName, expression, propertyPath. The full parameter table on this page comes from the server's own tool schema.
Register the Ae MCP server in PolicyLayer and add a rule for batch_set_expression: 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 Ae. Nothing to install.
batch_set_expression 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 batch_set_expression 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 batch_set_expression. 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.
batch_set_expression is provided by the Ae MCP server (@synthetic-ai/ae-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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