Run a MongoDB aggregation pipeline against a sift's records.
AI agents invoke aggregate_sift to trigger actions in Sifter. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
Executing an arbitrary MongoDB aggregation pipeline can include stages like $out or $merge that write/overwrite collections, $lookup for cross-collection joins, or $graphLookup. While aggregations are often read-only, the ability to run arbitrary pipeline stages means the tool can have side effects beyond simple reads. The 'Run ...
From the tool's definition "Run a MongoDB aggregation pipeline against a sift's records"
Documented attack patterns abuse exactly the kind of access aggregate_sift gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Sifter, and nothing reaches the server without passing your rules. This is the rule we recommend for aggregate_sift:
{
"version": "1",
"default": "deny",
"tools": {
"aggregate_sift": {
"limits": [
{
"counter": "aggregate_sift_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}aggregate_sift stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Run a MongoDB aggregation pipeline against a sift's records. It is categorised as a Execute tool in the Sifter MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Sifter MCP server in PolicyLayer and add a rule for aggregate_sift: 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 Sifter. Nothing to install.
aggregate_sift is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the aggregate_sift 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 aggregate_sift. 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.
aggregate_sift is provided by the Sifter MCP server (sifter-ai/sifter). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 15 Sifter tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
15 Sifter tools catalogued and risk-classified — across an index of 42,500+ MCP servers.