AI agents use set_secret_value to create or update resources in Neptune MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Neptune MCP Server environment.
Set operations that modify secrets are Write category—they create or modify data reversibly. Severity is high because secrets are sensitive; misuse could expose credentials or modify authentication mechanisms. Confidence is 0.85 rather than higher because the description is empty, but the name and server context strongly suggest this writes/updates secret values in AWS.
From the tool's definition Tool name 'set_secret_value' indicates modification of secret/credential data. No description provided, but context shows this is part of an AWS DevOps deployment tool (Neptune MCP Server) with other management capabilities like deploy_project and…
Documented attack patterns abuse exactly the kind of access set_secret_value gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Neptune MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for set_secret_value:
{
"version": "1",
"default": "deny",
"tools": {
"set_secret_value": {
"limits": [
{
"counter": "set_secret_value_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_secret_value 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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set_secret_value. It is categorised as a Write tool in the Neptune MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Neptune MCP Server MCP server in PolicyLayer and add a rule for set_secret_value: 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 Neptune MCP Server. Nothing to install.
set_secret_value 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 set_secret_value 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 set_secret_value. 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.
set_secret_value is provided by the Neptune MCP Server MCP server (shuttle-hq/neptune-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Neptune MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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15 Neptune MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.