Compute NDVI (Normalized Difference Vegetation Index) and save to GeoTIFF. Parameters: - source: input raster path. - red_band_index: index of red band (1-based). - nir_band_index: index of near-infrared band (1-based). - destination: output NDVI raster path.
AI agents use compute_ndvi to create or update resources in GIS MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your GIS MCP Server environment.
The tool performs a read operation on source raster data (retrieves red and NIR bands) but the primary action is writing a new derived dataset (NDVI raster) to disk. This is a Write operation rather than Read because the tool creates new persistent data.
From the tool's definition The tool computes NDVI data and explicitly saves output to a GeoTIFF file at a destination path ('save to GeoTIFF', 'destination: output NDVI raster path'). This constitutes creation/modification of data on the filesystem.
Documented attack patterns abuse exactly the kind of access compute_ndvi gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and GIS MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for compute_ndvi:
{
"version": "1",
"default": "deny",
"tools": {
"compute_ndvi": {
"limits": [
{
"counter": "compute_ndvi_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}compute_ndvi stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Compute NDVI (Normalized Difference Vegetation Index) and save to GeoTIFF. Parameters: - source: input raster path. - red_band_index: index of red band (1-based). - nir_band_index: index of near-infrared band (1-based). - destination: output NDVI raster path. It is categorised as a Write tool in the GIS MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the GIS MCP Server MCP server in PolicyLayer and add a rule for compute_ndvi: 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 GIS MCP Server. Nothing to install.
compute_ndvi is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the compute_ndvi 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 compute_ndvi. 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.
compute_ndvi is provided by the GIS MCP Server MCP server (mahdin75/gis-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from GIS MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
98 GIS MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.