Convert a 3-word address ("filled.count.soap") to a lat/lon centre + 3m×3m bounding box.
Part of the What3words server.
Free to start. No card required.
AI agents call words_to_coords to retrieve information from What3words 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 words_to_coords 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": {
"words_to_coords": {}
}
}See the full What3words policy for all 24 tools.
These attack patterns abuse exactly the kind of access words_to_coords 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.
Convert a 3-word address ("filled.count.soap") to a lat/lon centre + 3m×3m bounding box.. It is categorised as a Read tool in the What3words MCP Server, which means it retrieves data without modifying state.
Register the What3words MCP server in PolicyLayer and add a rule for words_to_coords: 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 What3words. Nothing to install.
words_to_coords 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 words_to_coords 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 words_to_coords. 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.
words_to_coords is provided by the What3words MCP server (https://gateway.pipeworx.io/what3words/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 24 What3words tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.