hk-spatial-mcp

geometry_op

Project, buffer, or simplify a GeoJSON geometry via Esri's public Geometry service without an API key. Convert between spatial references, expand features by distance, or reduce vertex density.

Instructions

Project, buffer or simplify one GeoJSON geometry with Esri's public Geometry service — no key.

operation: "project" (in_sr -> out_sr, e.g. 2326 -> 4326), "buffer" (distance in unit), "simplify" (max_deviation in the input SR's units).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "operation": "<operation>",
      "geojson": "<geojson>"
    },
    "name": "geometry_op"
  }
}

Input Schema

Name	Required	Default
`unit`	No	meters
`in_sr`	No
`out_sr`	No
`geojson`	Yes
`distance`	No
`operation`	Yes
`max_deviation`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.12.0Oct 23, 2026

TDQS

A3.7/5.0

Behavior3/5

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

With no annotations, the description carries the full behavioral burden, but it does disclose useful context: it uses Esri's public Geometry service and requires no key. It does not mention remote-call implications, rate limits, error behavior, or whether the input geometry is left unchanged, leaving meaningful gaps for an unannotated tool.

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?

The description is short, front-loaded, and wastes no words. The operation breakdown is compact and directly tied to invocation choices.

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

Completeness3/5

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

The output schema exists, so return values need not be described. Still, for a 7-parameter, unannotated tool with 0% schema description coverage, the description is only partially complete: it covers the main operation-to-parameter relationships but omits unit vocabularies, validation expectations, and service limitations.

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 description coverage is 0%, so the description must compensate. It usefully maps operation modes to parameters: project uses in_sr/out_sr, buffer uses distance with unit, and simplify uses max_deviation in input SR units. It still leaves unit allowed values, SR ID expectations, geojson format details, and optional-parameter behavior unexplained.

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 names three specific operations (project, buffer, simplify) on a clearly scoped resource: one GeoJSON geometry. It also identifies the backing service, Esri's public Geometry service, so an agent can distinguish this computational geometry tool from the data, map, geocode, and export siblings.

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

Usage Guidelines3/5

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

The operation-specific notes imply when each mode is appropriate: project for SR conversion, buffer for distance expansion, simplify for deviation reduction. However, there is no explicit when-to-use or when-not-to-use guidance and no comparison against siblings such as build_map or arcgis_request.

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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