AI agents use update to create or update resources in Things — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Things environment.
Based on the server's stated purpose of managing todos and projects via URL scheme, an 'update' tool most likely modifies existing data (todos or projects) reversibly. This is a Write operation. Severity is medium because unintended modifications could disrupt user productivity data, though changes are typically reversible.
From the tool's definition Tool is named 'update' on a server described as integrating with Things app to 'create, update, and manage todos and projects.' The tool name and server context strongly suggest data modification capability.
Documented attack patterns abuse exactly the kind of access update gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Things, and nothing reaches the server without passing your rules. This is the rule we recommend for update:
{
"version": "1",
"default": "deny",
"tools": {
"update": {
"limits": [
{
"counter": "update_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update 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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update. It is categorised as a Write tool in the Things MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Things MCP server in PolicyLayer and add a rule for update: 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 Things. Nothing to install.
update 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 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. 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 is provided by the Things MCP server (jimfilippou/things-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Things, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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8 Things tools catalogued and risk-classified — across an index of 43,000+ MCP servers.