List variables available in a dataset. Returns variable codes, labels, and concepts.
AI agents call list_variables to retrieve information from Census API MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and lists metadata about available variables in Census datasets. It performs a query operation that returns information without modifying, deleting, or executing anything. The output is informational only, making it a straightforward Read operation with minimal risk.
From the tool's definition Tool name 'list_variables' and description 'List variables available in a dataset. Returns variable codes, labels, and concepts.' indicate a retrieval operation with no side effects.
Attacks that exploit this kind of access
List variables available in a dataset. Returns variable codes, labels, and concepts. It is categorised as a Read tool in the Census API MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Census API MCP Server MCP server in PolicyLayer and add a rule for list_variables: 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 Census API MCP Server. Nothing to install.
list_variables is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list_variables 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 list_variables. 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.
list_variables is provided by the Census API MCP Server MCP server (shawndrake2/mcp-census). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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