list_expression_errors

List all layers and properties in a comp that have expression errors.

SERVERAe SOURCE@synthetic-ai/ae-mcp

Low RISK CLASS

Category Read

Parameters 31 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/synthetic-ai-ae-mcp/list-expression-errors.md

WHAT IT DOES

What list_expression_errors does on Ae

AI agents call list_expression_errors to retrieve information from Ae without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

Parameter	Type	Required
`compName`	string	Yes
`timeoutMs`	number	—
`projectPath`	string	—

Parameters from the server's own tool schema.

RISK

Why list_expression_errors is rated Low

Even though list_expression_errors only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs list_expression_errors 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 list_expression_errors, this is the rule to start with:

list_expression_errors Allowed

list_expression_errors is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_expression_errors": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Ae, apply this rule, and every list_expression_errors call is checked against it from then on.

FAQ

Questions about list_expression_errors

What does the list_expression_errors tool do? +

List all layers and properties in a comp that have expression errors. It is categorised as a Read tool in the Ae MCP Server, which means it retrieves data without modifying state.

What parameters does list_expression_errors accept? +

list_expression_errors accepts 3 parameters: compName, timeoutMs, projectPath. Required: compName. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on list_expression_errors? +

Register the Ae MCP server in PolicyLayer and add a rule for list_expression_errors: 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.

What risk level is list_expression_errors? +

list_expression_errors is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit list_expression_errors? +

Yes. Add a rate_limit block to the list_expression_errors 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.

How do I block list_expression_errors completely? +

Set action: deny in the PolicyLayer policy for list_expression_errors. 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.

What MCP server provides list_expression_errors? +

list_expression_errors 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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