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geo_simplify

Reduce the number of coordinates in a polyline while keeping its shape (Douglas-Peucker). tolerance_deg is in DEGREES, not metres: about 0.0001 drops detail finer than roughly 10 m at the equator. Endpoints are always kept. Returns the retained points and how many were removed. Local computation: no network call, no quota.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
pointsYesThe polyline's coordinates, 2 or more.
tolerance_degYesDouglas-Peucker tolerance in **degrees**, not metres. Around 0.0001 drops detail finer than roughly 10 m at the equator.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
pointsYesThe retained coordinates, endpoints always preserved.
removedYesHow many coordinates were removed.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed10 schema fields changed
    • addedInput schema / $defs / LatLon / anyOf
      Added value: +[
+  {
+    "properties": {
+      "lat": {
+        "description": "Latitude in decimal degrees (−90 to 90).",
+        "format": "double",
+        "type": "number"
+      },
+      "lon": {
+        "description": "Longitude in decimal degrees (−180 to 180).",
+        "format": "double",
+        "type": "number"
+      }
+    },
+    "required": [
+      "lat",
+      "lon"
+    ],
+    "type": "object"
+  },
+  {
+    "description": "GeoJSON position [lon, lat]: longitude FIRST.",
+    "items": {
+      "format": "double",
+      "type": "number"
+    },
+    "maxItems": 2,
+    "minItems": 2,
+    "type": "array"
+  }
+]
    • changedInput schema / $defs / LatLon / description
      Previous value: -"A WGS84 coordinate pair in decimal degrees."New value: +"A WGS84 coordinate in decimal degrees: a {lat, lon} object (preferred), or a GeoJSON [lon, lat] array with LONGITUDE FIRST, the same order as every polygon field on this server."
    • removedInput schema / $defs / LatLon / properties
      Removed value: -{
-  "lat": {
-    "description": "Latitude in decimal degrees (−90 to 90).",
-    "format": "double",
-    "type": "number"
-  },
-  "lon": {
-    "description": "Longitude in decimal degrees (−180 to 180).",
-    "format": "double",
-    "type": "number"
-  }
-}
    • removedInput schema / $defs / LatLon / required
      Removed value: -[
-  "lat",
-  "lon"
-]
    • removedInput schema / $defs / LatLon / type
      Removed value: -"object"
    • addedOutput schema / $defs / LatLon / anyOf
      Added value: +[
+  {
+    "properties": {
+      "lat": {
+        "description": "Latitude in decimal degrees (−90 to 90).",
+        "format": "double",
+        "type": "number"
+      },
+      "lon": {
+        "description": "Longitude in decimal degrees (−180 to 180).",
+        "format": "double",
+        "type": "number"
+      }
+    },
+    "required": [
+      "lat",
+      "lon"
+    ],
+    "type": "object"
+  },
+  {
+    "description": "GeoJSON position [lon, lat]: longitude FIRST.",
+    "items": {
+      "format": "double",
+      "type": "number"
+    },
+    "maxItems": 2,
+    "minItems": 2,
+    "type": "array"
+  }
+]
    • changedOutput schema / $defs / LatLon / description
      Previous value: -"A WGS84 coordinate pair in decimal degrees."New value: +"A WGS84 coordinate in decimal degrees: a {lat, lon} object (preferred), or a GeoJSON [lon, lat] array with LONGITUDE FIRST, the same order as every polygon field on this server."
    • removedOutput schema / $defs / LatLon / properties
      Removed value: -{
-  "lat": {
-    "description": "Latitude in decimal degrees (−90 to 90).",
-    "format": "double",
-    "type": "number"
-  },
-  "lon": {
-    "description": "Longitude in decimal degrees (−180 to 180).",
-    "format": "double",
-    "type": "number"
-  }
-}
    • removedOutput schema / $defs / LatLon / required
      Removed value: -[
-  "lat",
-  "lon"
-]
    • removedOutput schema / $defs / LatLon / type
      Removed value: -"object"
  2. First observed

TDQS

A4.7/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses unit semantics (degrees not metres), an approximate conversion to metres, endpoint preservation, return contents, and the fact that computation is local with no network call or quota. This is unusually thorough and lets an agent predict side effects and cost.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three tight sentences carry the essential information: purpose, unit warning, endpoint behavior, returns, and local computation. The most critical caveat (degrees not metres) is front-loaded, and every sentence earns its place without redundant prose.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter tool with an output schema, the description covers all agent-critical aspects: purpose, input units with magnitude intuition, endpoint guarantee, return shape, and execution characteristics. An agent has everything needed to invoke it correctly; any remaining details, such as coordinate format variants, are already fully handled by the rich input schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema already describes both parameters with 100% coverage, so the baseline is 3. The description adds genuine value beyond the schema by quantifying the tolerance in real-world terms ('0.0001 drops detail finer than roughly 10 m at the equator') and by clarifying that endpoints are always kept, which affects how the points parameter is interpreted.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('Reduce the number of coordinates') and a concrete resource ('a polyline') while naming the algorithm (Douglas-Peucker). This clearly distinguishes it from sibling geo tools like geo_length or geo_area, which perform different operations on geometries.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear context: this tool is for reducing coordinate density while preserving shape. It implies when to use it, though it does not explicitly name alternatives or state when not to use it. For a tool with a specialized geographic purpose, that context is sufficient for an agent to choose it over siblings.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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