Look up Autonomous System Number (ASN) for a domain or IP: AS number, organization, IPv4/IPv6 prefixes. Use to identify network operator and IP range ownership. Default returns first 50 prefixes per family — set include_full_prefixes=True for full list. Free: 30/hr, Pro: 500/hr. Returns {asn, asn...
Part of the ContrastAPI MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
AI agents call asn_lookup to retrieve information from ContrastAPI 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 asn_lookup 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.
tools:
asn_lookup:
rules:
- action: allowSee the full ContrastAPI policy for all 53 tools.
Agents calling read-class tools like asn_lookup have been implicated in these attack patterns. Read the full case and prevention policy for each:
Other tools in the Read risk category across the catalogue. The same policy patterns (rate-limit, allow) apply to each.
Look up Autonomous System Number (ASN) for a domain or IP: AS number, organization, IPv4/IPv6 prefixes. Use to identify network operator and IP range ownership. Default returns first 50 prefixes per family — set include_full_prefixes=True for full list. Free: 30/hr, Pro: 500/hr. Returns {asn, asn_name, ipv4_prefixes, ipv6_prefixes, ipv4_count, ipv6_count}.. It is categorised as a Read tool in the ContrastAPI MCP Server, which means it retrieves data without modifying state.
Add a rule in your Intercept YAML policy under the tools section for asn_lookup. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the ContrastAPI MCP server.
asn_lookup 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 asn_lookup rule in your Intercept 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 Intercept policy for asn_lookup. 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.
asn_lookup is provided by the ContrastAPI MCP server (contrastcyber/contrastapi). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic policy on every MCP tool call. Per-identity grants. Full audit log.