Get stream-level metrics. metric_set: 'storage'.
AI agents call stream_metrics to retrieve information from S2 StreamStore MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves metrics about a data stream, which is a read-only operation that queries existing data without creating, modifying, deleting, or executing external operations. It poses minimal risk as it only exposes monitoring/observability information about stream storage.
From the tool's definition Tool name 'stream_metrics' and description 'Get stream-level metrics' indicate a retrieval operation with no side effects. The metric_set parameter 'storage' is a query filter, not an action that modifies or deletes data.
Attacks that exploit this kind of access
Get stream-level metrics. metric_set: 'storage'. It is categorised as a Read tool in the S2 StreamStore MCP Server MCP Server, which means it retrieves data without modifying state.
Register the S2 StreamStore MCP Server MCP server in PolicyLayer and add a rule for stream_metrics: 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 S2 StreamStore MCP Server. Nothing to install.
stream_metrics 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 stream_metrics 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 stream_metrics. 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.
stream_metrics is provided by the S2 StreamStore MCP Server MCP server (s2-streamstore/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
stream_metrics is one line of S2 StreamStore MCP Server'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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