Merges two shapefiles based on common attribute columns, This function performs a database-style join, not a spatial join. Args: left_shapefile_path: Path to the left shapefile. The geometry from this file is preserved. right_shapefile_path: Path to the right shapefile to merge. output_path: Path...
AI agents use merge_gpd 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.
This tool creates or modifies data in a reversible manner (Write category). It combines two shapefiles into a new output file via a database-style join, which is a data creation/transformation operation.
From the tool's definition Tool description states it 'Merges two shapefiles' and 'saves the merged output shapefile' to 'output_path', creating a new geospatial data file. The function modifies data through a join/merge operation that results in a new shapefile being written to disk.
Documented attack patterns abuse exactly the kind of access merge_gpd 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 merge_gpd:
{
"version": "1",
"default": "deny",
"tools": {
"merge_gpd": {
"limits": [
{
"counter": "merge_gpd_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}merge_gpd 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.
Merges two shapefiles based on common attribute columns, This function performs a database-style join, not a spatial join. Args: left_shapefile_path: Path to the left shapefile. The geometry from this file is preserved. right_shapefile_path: Path to the right shapefile to merge. output_path: Path to save the merged output shapefile. how: Type of merge. One of 'left', 'right', 'outer', 'inner'. Defaults to 'inner'. on: Column name to join on. Must be found in both shapefiles. left_on: Column name to join on in the left shapefile. right_on: Column name to join on in the right shapefile. suffixes: Suffix to apply to overlapping column names. 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 merge_gpd: 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.
merge_gpd 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 merge_gpd 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 merge_gpd. 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.
merge_gpd 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.