When your task requires a paper-trail on the other end — loan paperwork to a bank, signed contract to a notary, booking confirmation to a hotel in Japan — send a fax to any number worldwide. Two modes: 'pdf' (fetch from public URL) or 'text' (we format typed text into a PDF locally). Optional cov...
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AI agents use send_fax to create or modify resources in Sats4AI - Bitcoin-Powered AI Tools. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call send_fax repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Sats4AI - Bitcoin-Powered AI Tools.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"send_fax": {
"limits": [
{
"counter": "send_fax_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Sats4AI - Bitcoin-Powered AI Tools policy for all 49 tools.
These attack patterns abuse exactly the kind of access send_fax gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
When your task requires a paper-trail on the other end — loan paperwork to a bank, signed contract to a notary, booking confirmation to a hotel in Japan — send a fax to any number worldwide. Two modes: 'pdf' (fetch from public URL) or 'text' (we format typed text into a PDF locally). Optional cover page. Pricing: 500 sats for up to 10 pages, +50 sats per additional page. Max 350 pages / 50 MB. Pass 'pages' to create_payment as 'quantity' to get the right invoice. Pay with Bitcoin Lightning — no fax machine, no phone line, no telecom account.. It is categorised as a Write tool in the Sats4AI - Bitcoin-Powered AI Tools MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Sats4AI - Bitcoin-Powered AI Tools MCP server in PolicyLayer and add a rule for send_fax: 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 Sats4AI - Bitcoin-Powered AI Tools. Nothing to install.
send_fax 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 send_fax 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 send_fax. 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.
send_fax is provided by the Sats4AI - Bitcoin-Powered AI Tools MCP server (cnghockey/sats4ai-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 49 Sats4AI - Bitcoin-Powered AI Tools tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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