Updates an existing user story in the Agile Development 2.0 module.
AI agents use update_story to create or update resources in Snow — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Snow environment.
This tool modifies data reversibly—it updates a user story record without deleting or destroying information. While updates in a project management context could affect workflows and downstream processes, the action is not irreversible and represents standard data modification (Write category).
From the tool's definition Tool name 'update_story' and description 'Updates an existing user story' indicate modification of existing data in ServiceNow's Agile Development module.
Documented attack patterns abuse exactly the kind of access update_story gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Snow, and nothing reaches the server without passing your rules. This is the rule we recommend for update_story:
{
"version": "1",
"default": "deny",
"tools": {
"update_story": {
"limits": [
{
"counter": "update_story_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_story stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Updates an existing user story in the Agile Development 2.0 module. It is categorised as a Write tool in the Snow MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Snow MCP server in PolicyLayer and add a rule for update_story: 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 Snow. Nothing to install.
update_story 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 update_story 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 update_story. 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.
update_story is provided by the Snow MCP server (shunyaai/snow-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Snow, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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88 Snow tools catalogued and risk-classified — across an index of 43,000+ MCP servers.