describe_table
Return full field schema for a ServiceNow table using sys_dictionary — includes field types, reference targets, mandatory/unique flags, and parent table. More accurate than get_table_schema for empty tables or custom tables.
This record as markdown: /tools/tedorigawa001-servicenow-mcp/describe-table.md
What describe_table does on ServiceNow-MCP
AI agents call describe_table to retrieve information from ServiceNow-MCP without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why describe_table is rated Low
describe_table is a metadata introspection tool. It retrieves schema information about ServiceNow tables without side effects. The operation is non-destructive and non-modifying. While metadata disclosure could theoretically inform reconnaissance for other attacks, the tool itself performs only a read operation.
From the tool's definition Tool description states it 'returns full field schema' — a retrieval operation. No mention of modification, deletion, execution, or financial operations.
Attacks that exploit this kind of access
The rule that runs describe_table safely
PolicyLayer is an MCP gateway: it sits between your AI agents and ServiceNow-MCP, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For describe_table, this is the rule to start with:
describe_table is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect ServiceNow-MCP, apply this rule, and every describe_table call is checked against it from then on.
Questions about describe_table
Return full field schema for a ServiceNow table using sys_dictionary — includes field types, reference targets, mandatory/unique flags, and parent table. More accurate than get_table_schema for empty tables or custom tables. It is categorised as a Read tool in the ServiceNow-MCP MCP Server, which means it retrieves data without modifying state.
Register the ServiceNow MCP server in PolicyLayer and add a rule for describe_table: 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 ServiceNow-MCP. Nothing to install.
describe_table 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 describe_table 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 describe_table. 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.
describe_table is provided by the ServiceNow MCP server (tedorigawa001/servicenow-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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