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ArcGIS Pro MCP

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add_field

Adds a new field to an ArcGIS Pro layer or table, specifying name, type, and properties like alias, domain, and length.

Instructions

Add a field to a layer or table.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
map_nameNoMap to act on; defaults to the active map.
nullableNoNULLABLE or NON_NULLABLE.NULLABLE
field_nameYesNew field name.
field_typeNoTEXT, LONG, SHORT, DOUBLE, FLOAT, DATE, BIGINTEGER, GUID or BLOB.TEXT
layer_nameYesLayer or table name as shown by get_layers, or a full dataset path.
field_aliasNoDisplay alias.
field_scaleNoNumeric scale.
field_domainNoAttribute domain to assign.
field_lengthNoLength for TEXT fields.
field_precisionNoNumeric precision.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed10 schema fields changedv1.1.1
    • addedInput schema / properties / field_alias / description
      Added value: +"Display alias."
    • addedInput schema / properties / field_domain
      Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Attribute domain to assign.",
+  "title": "Field Domain"
+}
    • addedInput schema / properties / field_length / description
      Added value: +"Length for TEXT fields."
    • addedInput schema / properties / field_name / description
      Added value: +"New field name."
    • addedInput schema / properties / field_precision
      Added value: +{
+  "anyOf": [
+    {
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Numeric precision.",
+  "title": "Field Precision"
+}
    • addedInput schema / properties / field_scale
      Added value: +{
+  "anyOf": [
+    {
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Numeric scale.",
+  "title": "Field Scale"
+}
    • addedInput schema / properties / field_type / description
      Added value: +"TEXT, LONG, SHORT, DOUBLE, FLOAT, DATE, BIGINTEGER, GUID or BLOB."
    • addedInput schema / properties / layer_name / description
      Added value: +"Layer or table name as shown by get_layers, or a full dataset path."
    • addedInput schema / properties / map_name / description
      Added value: +"Map to act on; defaults to the active map."
    • addedInput schema / properties / nullable
      Added value: +{
+  "default": "NULLABLE",
+  "description": "NULLABLE or NON_NULLABLE.",
+  "title": "Nullable",
+  "type": "string"
+}
  2. First observedv0.1.0

TDQS

C2.9/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does not say what happens if the field already exists, whether a schema lock or edit session is required, whether the operation is reversible, or what the response contains — significant gaps for a mutation tool with zero annotation coverage.

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

Conciseness4/5

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

A single efficient sentence with the action front-loaded and zero waste. It is well-formed, though the terseness is arguably under-specification rather than disciplined conciseness.

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

Completeness2/5

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

For a 10-parameter mutation tool with no annotations, the one-sentence description is not complete: it omits prerequisites (schema locks, edit sessions), failure behavior, and any routing versus add_fields/alter_field. The presence of an output schema excuses it from explaining return values, but not from the rest.

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 100% across all 10 parameters (map_name, field_type, nullable, field_domain, etc.), so the schema already explains each argument thoroughly. The description adds nothing beyond the schema, so the baseline 3 applies.

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

Purpose4/5

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

States a specific verb (Add) and resource (field) plus its targets (a layer or table), which is clear enough for an agent to know what the tool does. However, it does nothing to distinguish itself from the sibling add_fields (plural), so an agent cannot tell which one to pick without inspecting both schemas.

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

Usage Guidelines2/5

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

There is no when-to-use guidance, no prerequisites, and no mention of alternatives such as add_fields, alter_field, or delete_field. The agent must infer the single-field scope from the tool name alone.

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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