AI agents call tweak_prompt as a supporting operation in Promptheus workflows.
The name suggests minor modification of a prompt (text manipulation), which would typically be a Write or Read operation. However, given the sibling tools (list_models, list_providers, refine_prompt, validate_environment) this appears to be a prompt engineering server. 'Tweak' implies small adjustments to prompt text — likely a local transformation with no external side effects, similar to 'refine_prompt'.
From the tool's definition Tool name is 'tweak_prompt'; description is empty and uninformative.
Documented attack patterns abuse exactly the kind of access tweak_prompt gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Promptheus, and nothing reaches the server without passing your rules. This is the rule we recommend for tweak_prompt:
{
"version": "1",
"default": "deny",
"tools": {
"tweak_prompt": {
"limits": [
{
"counter": "tweak_prompt_rate",
"window": "minute",
"max": 60,
"scope": "grant"
}
]
}
}
}tweak_prompt gets a rate cap, and everything else on the server is denied unless you say otherwise.
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tweak_prompt. It is categorised as a Other tool in the Promptheus MCP Server, which means it performs auxiliary operations.
Register the Promptheus MCP server in PolicyLayer and add a rule for tweak_prompt: 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 Promptheus. Nothing to install.
tweak_prompt is a Other tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the tweak_prompt 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 tweak_prompt. 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.
tweak_prompt is provided by the Promptheus MCP server (pypi:promptheus). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Promptheus, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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5 Promptheus tools catalogued and risk-classified — across an index of 43,000+ MCP servers.