AI agents use add_trials to create or update resources in Optuna MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Optuna MCP Server environment.
This tool creates or modifies data in the Optuna study by adding new trial records. This is a reversible operation (trials can be removed or studies recreated), so it falls under Write rather than Execute or Destructive. The severity is medium because while it modifies study state, the blast radius is limited to the study's trial history and doesn't directly execute code or delete data.
From the tool's definition Tool name is 'add_trials' and description states 'Add multiple trials to the study' - the verb 'add' indicates creation/modification of data within the optimization study.
Documented attack patterns abuse exactly the kind of access add_trials gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Optuna MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for add_trials:
{
"version": "1",
"default": "deny",
"tools": {
"add_trials": {
"limits": [
{
"counter": "add_trials_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_trials 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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Add multiple trials to the study. It is categorised as a Write tool in the Optuna MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Optuna MCP Server MCP server in PolicyLayer and add a rule for add_trials: 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 Optuna MCP Server. Nothing to install.
add_trials 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 add_trials 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 add_trials. 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.
add_trials is provided by the Optuna MCP Server MCP server (optuna/optuna-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 26 Optuna MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
26 Optuna MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.