AI agents call hs_list_properties to retrieve information from Hubspot without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns metadata about CRM object properties. It performs no creation, modification, deletion, or execution of external operations. The blast radius of misuse is minimal—an agent could learn the schema of custom fields but cannot alter data or trigger actions. Classified as Read.
From the tool's definition Tool name 'hs_list_properties' and description 'List all properties defined for a CRM object type' indicate a retrieval operation with no side effects. The ability to filter with 'customOnly=true' parameter does not introduce state changes.
Attacks that exploit this kind of access
List all properties defined for a CRM object type. Use customOnly=true to see only custom fields. It is categorised as a Read tool in the Hubspot MCP Server, which means it retrieves data without modifying state.
Register the Hubspot MCP server in PolicyLayer and add a rule for hs_list_properties: 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 Hubspot. Nothing to install.
hs_list_properties 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 hs_list_properties 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 hs_list_properties. 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.
hs_list_properties is provided by the Hubspot MCP server (zleventer/hubspot-mcp). 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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