Add a new column to a table by writing to sys_dictionary: column name, label, internal_type (string, integer, reference, etc.), and — for reference fields — the referenced table. Optional max_length and mandatory flag.
AI agents use snow_create_field to create or update resources in Serac — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Serac environment.
This tool creates new fields/columns in a ServiceNow table by modifying the sys_dictionary system table. While reversible (fields can be deleted), this is a schema-altering write operation that could break existing workflows, reports, or integrations if misused. The high severity reflects that an autonomous agent adding arbitrary fields to critical tables could cause business disruption.
From the tool's definition Tool description states 'Add a new column to a table by writing to sys_dictionary' — explicitly a write operation that creates new schema objects. Uses verbs 'Add' and 'writing to' which indicate modification of data structures.
Attacks that exploit this kind of access
Add a new column to a table by writing to sys_dictionary: column name, label, internal_type (string, integer, reference, etc.), and — for reference fields — the referenced table. Optional max_length and mandatory flag. It is categorised as a Write tool in the Serac MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Serac MCP server in PolicyLayer and add a rule for snow_create_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 Serac. Nothing to install.
snow_create_field is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the snow_create_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 snow_create_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.
snow_create_field is provided by the Serac MCP server (serac-labs/serac). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
snow_create_field is one line of Serac's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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