Save a custom strategy to disk for re-use.
AI agents use save_strategy to create or update resources in Momentum — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Momentum environment.
This tool creates or modifies data by writing a strategy configuration to disk. It is reversible (the file can be edited or deleted later), making it a Write action rather than Destructive. While it operates within a trading analysis context, it does not move money, execute trades, or delete data.
From the tool's definition Tool name 'save_strategy' combined with description 'Save a custom strategy to disk for re-use' indicates creation and persistence of data to storage.
Documented attack patterns abuse exactly the kind of access save_strategy gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Momentum, and nothing reaches the server without passing your rules. This is the rule we recommend for save_strategy:
{
"version": "1",
"default": "deny",
"tools": {
"save_strategy": {
"limits": [
{
"counter": "save_strategy_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}save_strategy 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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Save a custom strategy to disk for re-use. It is categorised as a Write tool in the Momentum MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Momentum MCP server in PolicyLayer and add a rule for save_strategy: 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 Momentum. Nothing to install.
save_strategy 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 save_strategy 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 save_strategy. 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.
save_strategy is provided by the Momentum MCP server (mphinance/momentum-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Momentum, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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52 Momentum tools catalogued and risk-classified — across an index of 43,000+ MCP servers.