AI agents call get_custom_field to retrieve information from Mycase without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves a custom field value without creating, modifying, deleting, or executing anything. It is a straightforward read operation with no side effects. The law firm context and access to case/client data present minimal risk when used for legitimate queries.
From the tool's definition Tool name and description: 'Get a custom field by ID' — the verb 'Get' and the absence of any modification language indicate a retrieval operation.
Attacks that exploit this kind of access
Get a custom field by ID. It is categorised as a Read tool in the Mycase MCP Server, which means it retrieves data without modifying state.
Register the Mycase MCP server in PolicyLayer and add a rule for get_custom_field: 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 Mycase. Nothing to install.
get_custom_field 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 get_custom_field 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 get_custom_field. 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.
get_custom_field is provided by the Mycase MCP server (rosenadvertising/mycase-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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