set_webhook
Register a webhook that fires when market conditions meet your criteria. Fathom evaluates conditions every 60 seconds and POSTs a JSON payload to your URL when all conditions are met. Example: alert me at my bot URL when fear_greed < 20 and regime == capitulation. Available fields: fear_greed, ri...
This record as markdown: /tools/0xhashy-fathom-fyi/set-webhook.md
What set_webhook does on Fathom Fyi
AI agents use set_webhook 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.
Why set_webhook is rated Medium
This is a Write operation because it creates and stores a new webhook configuration in the Fathom system. While webhooks are a standard integration pattern, the tool persists state (a webhook rule) that can trigger automated downstream actions.
From the tool's definition Tool registers (creates) a webhook endpoint by POSTing a JSON payload to a user-specified URL. The description explicitly states 'Register a webhook' and 'POSTs a JSON payload to your URL', indicating creation of a persistent notification mechanism.
Risk signalsBulk/mass operation — affects multiple targets
Attacks that exploit this kind of access
The rule that runs set_webhook 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_webhook, this is the rule to start with:
set_webhook 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Fathom Fyi, apply this rule, and every set_webhook call is checked against it from then on.
Questions about set_webhook
Register a webhook that fires when market conditions meet your criteria. Fathom evaluates conditions every 60 seconds and POSTs a JSON payload to your URL when all conditions are met. Example: alert me at my bot URL when fear_greed < 20 and regime == capitulation. Available fields: fear_greed, risk_score, opportunity_score, regime, posture, cycle_phase, tvl_change_7d, defi_health, macro_impact, net_flow_signal, leverage_signal, btc_put_call, btc_sp500_correlation, macro_risk_appetite. 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.
Register the Fathom Fyi MCP server in PolicyLayer and add a rule for set_webhook: 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.
set_webhook 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 set_webhook 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 set_webhook. 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.
set_webhook 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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