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Arcgis Fairfax

by io.github.pipeworx-io
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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.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
urlYesFeature/Map Service layer url ending in /FeatureServer/<n> or /MapServer/<n>.
limitNoMax features (1-2000, default 50).
whereNoSQL where clause, e.g. "STATE = 'CA' AND YEAR >= 2020". Default "1=1".
offsetNoPagination offset.
order_byNoe.g. "POP DESC".
out_fieldsNoComma-separated field names, or "*" for all (default).

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • addedInput schema / examples
      Added value: +[
+  {
+    "limit": 50,
+    "out_fields": "*",
+    "url": "https://gis.fairfaxcounty.gov/arcgis/rest/services/OpenData/Parcels/FeatureServer/0",
+    "where": "1=1"
+  },
+  {
+    "limit": 100,
+    "order_by": "INCIDENT_DATE DESC",
+    "out_fields": "INCIDENT_DATE,LOCATION,INCIDENT_TYPE",
+    "url": "https://gis.fairfaxcounty.gov/arcgis/rest/services/OpenData/PublicSafety/FeatureServer/0",
+    "where": "INCIDENT_TYPE = 'Theft'"
+  }
+]
  2. First observed

TDQS

A4.4/5.0
Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds valuable behavioral details: 'Returns attribute rows (and geometry)' and a practical sampling technique, which go beyond the annotations and help set expectations for output.

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?

Four short sentences, each earning its place: purpose, parameter summary, output shape, and usage tip. No filler or redundancy, and the most critical information is front-loaded.

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?

The description covers source (search_datasets), all key parameters, return shape, and a sampling pattern. Combined with rich annotations, it is sufficient for a read-only query tool. Minor gaps like pagination semantics and possible errors are not critical given the schema coverage.

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?

Schema coverage is 100% with descriptions and examples, so baseline is 3. The description adds value by summarizing the parameter syntax (SQL-like where, comma-separated out_fields) and highlighting the where='1=1' + out_fields='*' combination, enhancing practical understanding.

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 action ('Query an ArcGIS Feature Service / Map Service layer by its url'), names the exact resource, and references search_datasets as the source. This clearly distinguishes it from sibling tools like search_datasets (discovery) and layer_info (metadata).

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?

Provides clear context by indicating the URL comes from search_datasets, implying a workflow. Also gives a concrete usage tip: 'Use where="1=1" + out_fields="*" to sample.' However, it does not explicitly state when not to use or name alternatives like layer_info.

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

All Arcgis Fairfax toolsInspect
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