AI agents use stream_add to create or update resources in Awslabs Amazon Sns Sqs — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Awslabs Amazon Sns Sqs environment.
Given the empty description and the tool's position on a messaging service server, 'stream_add' most likely creates or modifies messages/data in SNS or SQS streams. This aligns with the Write category (creates/modifies data reversibly). Severity is medium because while the operation modifies data, it is typically reversible (messages can be deleted) and the blast radius depends on what data is added.
From the tool's definition Tool named 'stream_add' on Amazon SNS/SQS MCP Server; description is empty but naming convention suggests adding items to a stream/queue, which is a write operation that creates or modifies message stream data.
Documented attack patterns abuse exactly the kind of access stream_add gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Awslabs Amazon Sns Sqs, and nothing reaches the server without passing your rules. This is the rule we recommend for stream_add:
{
"version": "1",
"default": "deny",
"tools": {
"stream_add": {
"limits": [
{
"counter": "stream_add_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}stream_add 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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stream_add. It is categorised as a Write tool in the Awslabs Amazon Sns Sqs MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Awslabs Amazon Sns Sqs MCP server in PolicyLayer and add a rule for stream_add: 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 Awslabs Amazon Sns Sqs. Nothing to install.
stream_add 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 stream_add 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_add. 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_add is provided by the Awslabs Amazon Sns Sqs MCP server (awslabs.amazon-sns-sqs-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Awslabs Amazon Sns Sqs, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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