Get recent water level and streamflow data for a USGS monitoring site. Returns time-series data including discharge (streamflow) and gage height for the specified monitoring station. Args: site_number: USGS site number (e.g. '01646500' for Potomac River at Little Falls). days: Number of days of d...
Part of the USGS Water Monitoring server.
Free to start. No card required.
AI agents call get_water_levels to retrieve information from USGS Water Monitoring 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 get_water_levels 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": {
"get_water_levels": {}
}
}See the full USGS Water Monitoring policy for all 3 tools.
These attack patterns abuse exactly the kind of access get_water_levels 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.
Get recent water level and streamflow data for a USGS monitoring site. Returns time-series data including discharge (streamflow) and gage height for the specified monitoring station. Args: site_number: USGS site number (e.g. '01646500' for Potomac River at Little Falls). days: Number of days of data to retrieve (default 7, max 120).. It is categorised as a Read tool in the USGS Water Monitoring MCP Server, which means it retrieves data without modifying state.
Register the USGS Water Monitoring MCP server in PolicyLayer and add a rule for get_water_levels: 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 USGS Water Monitoring. Nothing to install.
get_water_levels 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 get_water_levels 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 get_water_levels. 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.
get_water_levels is provided by the USGS Water Monitoring MCP server (https://mcp.olyport.com/water/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 3 USGS Water Monitoring tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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