Place a conversational voice-AI phone call to a business on a consumer's behalf and return a structured answer. THE differentiated capability: reach the ~60M long-tail SMBs that have NO API and NO booking page — only a phone number. An AI agent cannot pick up a phone and hold a conversation; this...
Part of the Agent Broker server.
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AI agents call call_business to retrieve information from Agent Broker 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 call_business 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": {
"call_business": {}
}
}See the full Agent Broker policy for all 14 tools.
These attack patterns abuse exactly the kind of access call_business 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.
Place a conversational voice-AI phone call to a business on a consumer's behalf and return a structured answer. THE differentiated capability: reach the ~60M long-tail SMBs that have NO API and NO booking page — only a phone number. An AI agent cannot pick up a phone and hold a conversation; this tool does. Give a plain-language objective; the voice AI navigates the call and extracts the answer. Business-directed (B2B), far less restricted than calling consumers — but the compliance gate still enforces recording consent per jurisdiction. Async: returns a call handle; poll get_outcome for the transcript + extracted fields. WHEN TO USE: Use when the target business has NO booking URL and NO API — only a phone number — and the consumer asked the agent to reach them (e.g. 'call this plumber and ask if they can come Tuesday', 'ask the salon if they take walk-ins this afternoon'). Also use to confirm details a booking page doesn't expose (real-time availability, custom quotes). WHEN NOT TO USE: Do NOT use when the business has a booking URL — use import_booking_url + schedule_appointment (cheaper, faster, deterministic). Do NOT use for calls to consumers/individuals (this tool is for reaching businesses). Do NOT use for marketing or telemarketing — the compliance gate and the B2B-only framing reject that. COST: $0.5 per_call LATENCY: ~45000ms EXECUTION: async_by_default (use get_outcome to retrieve result). It is categorised as a Read tool in the Agent Broker MCP Server, which means it retrieves data without modifying state.
Register the Agent Broker MCP server in PolicyLayer and add a rule for call_business: 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 Agent Broker. Nothing to install.
call_business 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 call_business 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 call_business. 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.
call_business is provided by the Agent Broker MCP server (https://agent-broker-edge.basil-agent.workers.dev/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 14 Agent Broker tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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