Get historical air quality data for a site or location, with health context. Returns a 'narrative' with plain-English interpretation of trends, WHO guideline exceedances, and guideline comparisons. Present the narrative to users first. Also returns raw 'data' and 'summary' statistics. Args: start...
Part of the Hermes — Air Quality Intelligence server.
Free to start. No card required.
AI agents call get_historical_aq to retrieve information from Hermes — Air Quality Intelligence 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_historical_aq 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_historical_aq": {}
}
}See the full Hermes — Air Quality Intelligence policy for all 15 tools.
These attack patterns abuse exactly the kind of access get_historical_aq 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 historical air quality data for a site or location, with health context. Returns a 'narrative' with plain-English interpretation of trends, WHO guideline exceedances, and guideline comparisons. Present the narrative to users first. Also returns raw 'data' and 'summary' statistics. Args: start_date: Start date (ISO format, e.g. "2025-01-01"). end_date: End date (ISO format). location: Postcode, place name, or "lat,lon". Provide this or site_code. site_code: Direct site code. Provide this or location. pollutants: Optional filter, e.g. ["NO2", "PM2.5"]. frequency: "hourly", "daily", or "monthly" (default "daily").. It is categorised as a Read tool in the Hermes — Air Quality Intelligence MCP Server, which means it retrieves data without modifying state.
Register the Hermes — Air Quality Intelligence MCP server in PolicyLayer and add a rule for get_historical_aq: 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 Hermes — Air Quality Intelligence. Nothing to install.
get_historical_aq 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_historical_aq 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_historical_aq. 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_historical_aq is provided by the Hermes — Air Quality Intelligence MCP server (https://hermes.southlondonscientific.com/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 15 Hermes — Air Quality Intelligence tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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