Indicator-based market screener. The middle layer between raw price scan and LLM thesis edges. Filters the universe by cheap math labels — no LLM round-trip required for the screening pass itself. Indicators: IY (implied annualized yield %), CRI (cliff risk = max(p,1-p)/min(p,1-p)), OR (event ove...
Risk signalsHigh parameter count (20 properties)
Part of the Simplefunctions server.
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AI agents call screen_markets to retrieve information from Simplefunctions without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though screen_markets only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"screen_markets": {}
}
}See the full Simplefunctions policy for all 108 tools.
These attack patterns abuse exactly the kind of access screen_markets gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Indicator-based market screener. The middle layer between raw price scan and LLM thesis edges. Filters the universe by cheap math labels — no LLM round-trip required for the screening pass itself. Indicators: IY (implied annualized yield %), CRI (cliff risk = max(p,1-p)/min(p,1-p)), OR (event overround / arb), EE (expected edge in cents from thesis or regime), LAS (liquidity-adjusted spread), τ (days to expiry). Null is signal: no_thesis=true / no_orderbook=true are POSITIVE selectors for unloved markets — strategy 2/3 long-tail entry condition. Use this to bulk-discover candidates before paying any LLM cost. No auth required.. It is categorised as a Read tool in the Simplefunctions MCP Server, which means it retrieves data without modifying state.
Register the Simplefunctions MCP server in PolicyLayer and add a rule for screen_markets: 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 Simplefunctions. Nothing to install.
screen_markets is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the screen_markets 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 screen_markets. 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.
screen_markets is provided by the Simplefunctions MCP server (@spfunctions/cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 108 Simplefunctions tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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