Arcgis Dukescounty

Query Layer

query_layer

Read-onlyIdempotent

Query an ArcGIS Feature Service / Map Service layer by its url (from search_datasets). SQL-like where, comma-separated out_fields, order_by, limit, offset. Returns attribute rows (and geometry). Use where="1=1" + out_fields="*" to sample.

Example tool call

This call uses example arguments supplied in the tool’s input schema.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "url": "https://services.arcgis.com/dukes-county/arcgis/rest/services/Parcels/FeatureServer/0",
      "limit": 50,
      "where": "1=1",
      "out_fields": "*"
    },
    "name": "query_layer"
  }
}

Input Schema

Name	Required	Description
`url`	Yes	Feature/Map Service layer url ending in /FeatureServer/<n> or /MapServer/<n>.
`limit`	No	Max features (1-2000, default 50).
`where`	No	SQL where clause, e.g. "STATE = 'CA' AND YEAR >= 2020". Default "1=1".
`offset`	No	Pagination offset.
`order_by`	No	e.g. "POP DESC".
`out_fields`	No	Comma-separated field names, or "*" for all (default).

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedJul 29, 2026

addedInput schema / examples

Added value: +[
+  {
+    "limit": 50,
+    "out_fields": "*",
+    "url": "https://services.arcgis.com/dukes-county/arcgis/rest/services/Parcels/FeatureServer/0",
+    "where": "1=1"
+  },
+  {
+    "limit": 100,
+    "out_fields": "PARCEL_ID,ZONE_TYPE,ACRES",
+    "url": "https://services.arcgis.com/dukes-county/arcgis/rest/services/Zoning/FeatureServer/0",
+    "where": "ZONE_TYPE = 'Residential'"
+  }
+]

First observedJun 26, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true. The description adds behavioral context by noting it returns 'attribute rows (and geometry)' and uses SQL-like where clause and pagination, which goes beyond the annotations. No contradiction.

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?

Two sentences, front-loaded with the primary action, followed by parameter summary and return type. No wasted words.

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

Completeness4/5

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

With no output schema, the description explains the return format (attribute rows and geometry) and provides a usage tip. It covers the core workflow (use with search_datasets, sampling) and relies on schema for param details. Adequate, though it could mention error handling or service format constraints.

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

Parameters3/5

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

Schema coverage is 100%, so baseline is 3. The description repeats parameter names (where, out_fields, order_by, limit, offset) but doesn't add new syntax details beyond the schema. The sampling tip is a small value-add, so score remains at 3.

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 explicitly states 'Query an ArcGIS Feature Service / Map Service layer by its url' with a specific verb and resource. It distinguishes from sibling tools like search_datasets by noting the URL comes from search_datasets, and from layer_info by indicating it returns attribute rows and geometry.

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 provides clear context: the tool is for querying a specific layer URL obtained from search_datasets. It includes a practical sampling tip ('where="1=1" + out_fields="*"'), but does not explicitly mention when not to use it or alternatives beyond the implicit distinction from search_datasets.

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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