us-drought-monitor-mcp-server

Look up drought reference data

drought_list_reference

Read-onlyIdempotent

Look up drought categories, DSCI formulas, metric support, publication coverage and exact geography identifiers. Filter complete families by nameContains before paging. Use state for counties or climate_divisions; huc requires hucLevel 2, 4, 6 or 8 and accepts a shorter parentHuc. Follow nextCursor with the same filters to browse every match.

Input Schema

Name	Required	Description
`limit`	No	Default 25 records per page; values above 200 are clamped with disclosure.
`state`	No	County or climate-division filter: exact state postal code, two-digit FIPS or full name.
`topic`	Yes	Reference family to browse; river_forecast_centers provides official RFC codes and names.
`cursor`	No	Continuation cursor from the previous page with the same filters.
`hucLevel`	No	Required for huc; exact identifier width.
`parentHuc`	No	Existing parent HUC at level 2, 4 or 6, shorter than hucLevel; blank is omitted.
`nameContains`	No	All normalized tokens must appear in the reference name.

Output Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`topic`	No	Selected reference family.
`notice`	No	Guidance when no names match.
`hasMore`	No	Whether another page remains.
`records`	No	Complete records on this page.
`nextCursor`	No	Continuation with identical filters, or null.
`provenance`	No	Source attribution and acquisition time.
`totalCount`	No	Count after filtering, before pagination.
`limitNotice`	No	Disclosure when the requested limit was clamped.
`bundleVersion`	No	Generated reference bundle version.
`effectiveLimit`	No	Effective page ceiling after clamping to 200.
`sourceMetadata`	No	Source vintages and SHA-256 evidence.

Schema Changelog

Changes observed during successful MCP inspections.

Changed9 schema fields changedOct 26, 2026

changedInput schema / properties / limit / default
```
Previous value: -50New value: +25
```

changedInput schema / properties / limit / description

Previous value: -"Maximum records on this page; values above 200 are clamped with disclosure."New value: +"Default 25 records per page; values above 200 are clamped with disclosure."

changedInput schema / properties / topic / description

Previous value: -"Reference family to browse."New value: +"Reference family to browse; river_forecast_centers provides official RFC codes and names."

changedInput schema / properties / topic / enum

Previous value: -[
-  "categories",
-  "dsci",
-  "area_types",
-  "coverage",
-  "states",
-  "counties",
-  "tribal",
-  "climate_divisions",
-  "huc"
-]New value: +[
+  "categories",
+  "dsci",
+  "area_types",
+  "coverage",
+  "states",
+  "counties",
+  "tribal",
+  "climate_divisions",
+  "river_forecast_centers",
+  "huc"
+]

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode. Declared by this tool: `ambiguous_area`: Multiple exact normalized names match. `unknown_area`: The county state filter cannot resolve. `invalid_cursor`: The cursor is malformed or filters changed. `invalid_reference_filter`: Filters do not belong to the selected topic. `dataset_too_large`: A complete reference record exceeds the response budget. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `ambiguous_area`: Multiple exact normalized names match. `unknown_area`: The county state filter cannot resolve. `invalid_cursor`: The cursor is malformed or filters changed. `invalid_reference_filter`: Filters do not belong to the selected topic. Other values are possible when a failure originates below the handler."

changedOutput schema / properties / error / properties / data / properties / reason / examples

Previous value: -[
-  "ambiguous_area",
-  "unknown_area",
-  "invalid_cursor",
-  "invalid_reference_filter",
-  "dataset_too_large"
-]New value: +[
+  "ambiguous_area",
+  "unknown_area",
+  "invalid_cursor",
+  "invalid_reference_filter"
+]

addedOutput schema / properties / provenance / properties / populationInterpretation

Added value: +{
+  "additionalProperties": false,
+  "description": "Present when the workflow includes a supported population metric.",
+  "properties": {
+    "caveat": {
+      "description": "Population assumptions and precision limitations.",
+      "type": "string"
+    },
+    "methodologyUrl": {
+      "description": "Official population estimation methodology.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "methodologyUrl",
+    "caveat"
+  ],
+  "type": "object"
+}

changedOutput schema / properties / records / items / anyOf

Previous value: -[
-  {
-    "additionalProperties": false,
-    "description": "Canonical geography with source vintage.",
-    "properties": {
-      "areaType": {
-        "description": "Geography family.",
-        "enum": [
-          "us",
-          "state",
-          "county",
-          "huc",
-          "tribal",
-          "climate_division"
-        ],
-        "type": "string"
-      },
-      "currentUsdm": {
-        "description": "Whether the county appears in the acquisition-week USDM response.",
-        "type": "boolean"
-      },
-      "hucLevel": {
-        "anyOf": [
-          {
-            "const": 2,
-            "type": "number"
-          },
-          {
-            "const": 4,
-            "type": "number"
-          },
-          {
-            "const": 6,
-            "type": "number"
-          },
-          {
-            "const": 8,
-            "type": "number"
-          }
-        ],
-        "description": "HUC width for watershed areas."
-      },
-      "id": {
-        "description": "Canonical identifier, preserving leading zeroes.",
-        "type": "string"
-      },
-      "name": {
-        "description": "Source geography name.",
-        "type": "string"
-      },
-      "sourceVintage": {
-        "description": "Source dataset vintage.",
-        "type": "string"
-      },
-      "state": {
-        "description": "State postal code where known.",
-        "type": "string"
-      }
-    },
-    "required": [
-      "areaType",
-      "id",
-      "name",
-      "sourceVintage"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "description": "Named drought definition, coverage note or selector guidance.",
-    "properties": {
-      "categoricalFormula": {
-        "description": "DSCI formula using categorical area percentages.",
-        "type": "string"
-      },
-      "cumulativeFormula": {
-        "description": "DSCI formula using cumulative area percentages.",
-        "type": "string"
-      },
-      "description": {
-        "description": "Definition or interpretation.",
-        "type": "string"
-      },
-      "id": {
-        "description": "Reference record identifier.",
-        "type": "string"
-      },
-      "identifierFormat": {
-        "description": "Accepted identifier syntax.",
-        "type": "string"
-      },
-      "metrics": {
-        "description": "Supported public metrics.",
-        "items": {
-          "type": "string"
-        },
-        "type": "array"
-      },
-      "name": {
-        "description": "Reference label.",
-        "type": "string"
-      },
-      "percentile": {
-        "description": "Official example percentile range.",
-        "type": "string"
-      },
-      "spiSpei": {
-        "description": "Official SPI/SPEI range.",
-        "type": "string"
-      }
-    },
-    "required": [
-      "id",
-      "name",
-      "description"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "description": "Canonical geography with source vintage.",
+    "properties": {
+      "areaType": {
+        "description": "Geography family.",
+        "enum": [
+          "us",
+          "state",
+          "county",
+          "huc",
+          "tribal",
+          "climate_division",
+          "river_forecast_center"
+        ],
+        "type": "string"
+      },
+      "currentUsdm": {
+        "description": "Whether the county appears in the acquisition-week USDM response.",
+        "type": "boolean"
+      },
+      "hucLevel": {
+        "anyOf": [
+          {
+            "const": 2,
+            "type": "number"
+          },
+          {
+            "const": 4,
+            "type": "number"
+          },
+          {
+            "const": 6,
+            "type": "number"
+          },
+          {
+            "const": 8,
+            "type": "number"
+          }
+        ],
+        "description": "HUC width for watershed areas."
+      },
+      "id": {
+        "description": "Canonical identifier, preserving leading zeroes.",
+        "type": "string"
+      },
+      "name": {
+        "description": "Source geography name.",
+        "type": "string"
+      },
+      "sourceVintage": {
+        "description": "Source dataset vintage.",
+        "type": "string"
+      },
+      "state": {
+        "description": "State postal code where known.",
+        "type": "string"
+      }
+    },
+    "required": [
+      "areaType",
+      "id",
+      "name",
+      "sourceVintage"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "description": "Named drought definition, coverage note or selector guidance.",
+    "properties": {
+      "categoricalFormula": {
+        "description": "DSCI formula using categorical area percentages.",
+        "type": "string"
+      },
+      "cumulativeFormula": {
+        "description": "DSCI formula using cumulative area percentages.",
+        "type": "string"
+      },
+      "description": {
+        "description": "Definition or interpretation.",
+        "type": "string"
+      },
+      "id": {
+        "description": "Reference record identifier.",
+        "type": "string"
+      },
+      "identifierFormat": {
+        "description": "Accepted identifier syntax.",
+        "type": "string"
+      },
+      "metrics": {
+        "description": "Supported public metrics.",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "name": {
+        "description": "Reference label.",
+        "type": "string"
+      },
+      "percentile": {
+        "description": "Official example percentile range.",
+        "type": "string"
+      },
+      "spiSpei": {
+        "description": "Official SPI/SPEI range.",
+        "type": "string"
+      }
+    },
+    "required": [
+      "id",
+      "name",
+      "description"
+    ],
+    "type": "object"
+  }
+]

changedOutput schema / properties / topic / enum

Previous value: -[
-  "categories",
-  "dsci",
-  "area_types",
-  "coverage",
-  "states",
-  "counties",
-  "tribal",
-  "climate_divisions",
-  "huc"
-]New value: +[
+  "categories",
+  "dsci",
+  "area_types",
+  "coverage",
+  "states",
+  "counties",
+  "tribal",
+  "climate_divisions",
+  "river_forecast_centers",
+  "huc"
+]

First observedOct 24, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, closed-world, so the safety profile is covered. The description adds real behavior beyond that: cross-page filter consistency requirement for cursors, the parentHuc-must-be-shorter constraint, and that families are filtered before paging — all useful operational context.

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 dense sentences, front-loaded with the resource list, then filtering, geography constraints, and pagination — in the order an agent would need them. No filler or tautology.

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 an output schema present, return values need no explanation, and all seven parameters are addressed in context. Remaining gaps are minor: default ordering of results, and whether some topics (e.g. tribal) combine with state filtering.

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%, so baseline would be 3, but the description adds relationships the schema only states in isolation: which topic values pair with which geography parameters, and the coupling of parentHuc to hucLevel. That linkage meaningfully reduces mis-invocation risk.

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?

States a concrete verb ('look up') and enumerates the exact reference families (categories, DSCI formulas, metric support, coverage, geography identifiers), which cleanly separates it from the data-returning siblings like drought_get_timeseries or drought_get_current_severity. An agent can tell this is a static reference/metadata tool without opening the schema.

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?

Gives actionable routing rules: use state for counties or climate_divisions, huc requires hucLevel 2/4/6/8, and follow nextCursor with the same filters. It does not explicitly say when a sibling tool is the better choice (e.g. 'use drought_compare_areas instead for cross-area comparison'), so the alternative-selection guidance is implied rather than stated.

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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