set_signal_preferences

SERVERFathom Fyi SOURCE0xhashy/fathom-fyi

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade C, identity unverified Pull the record →

This record as markdown: /tools/0xhashy-fathom-fyi/set-signal-preferences.md

WHAT IT DOES

What set_signal_preferences does on Fathom Fyi

AI agents use set_signal_preferences to create or update resources in Fathom Fyi, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Fathom Fyi environment.

RISK

Why set_signal_preferences is rated Medium

This tool creates or modifies user configuration data (signal preferences) that persists across sessions. It is a Write operation—reversible modification of settings state. The severity is medium because misconfigured preferences could degrade decision-making quality in financial contexts (disabling critical signals), but the tool itself does not execute trades, move funds, or delete data.

From the tool's definition set_signal_preferences - Customize which signals feed into your reality check. Turn individual signal sources on or off... Preferences persist between sessions.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs set_signal_preferences safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Fathom Fyi, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For set_signal_preferences, this is the rule to start with:

set_signal_preferences Rate-limited

set_signal_preferences 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_signal_preferences": {
      "limits": [
        {
          "counter": "set_signal_preferences_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Fathom Fyi, apply this rule, and every set_signal_preferences call is checked against it from then on.

FAQ

Questions about set_signal_preferences

What does the set_signal_preferences tool do? +

Customize which signals feed into your reality check. Turn individual signal sources on or off. Regime and sentiment are always included. Preferences persist between sessions. Example: {weather: false, political_cycle: false} to disable those signals. It is categorised as a Write tool in the Fathom Fyi MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_signal_preferences? +

Register the Fathom Fyi MCP server in PolicyLayer and add a rule for set_signal_preferences: 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 Fathom Fyi. Nothing to install.

What risk level is set_signal_preferences? +

set_signal_preferences is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_signal_preferences? +

Yes. Add a rate_limit block to the set_signal_preferences 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.

How do I block set_signal_preferences completely? +

Set action: deny in the PolicyLayer policy for set_signal_preferences. 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.

What MCP server provides set_signal_preferences? +

set_signal_preferences is provided by the Fathom Fyi MCP server (0xhashy/fathom-fyi). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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