EPA EJScreen

get_demographic_indicators

Get demographic vulnerability indicators by block group.

Returns demographic data including minority percentage, low income
percentage, linguistic isolation, education levels, and age
distributions. These are the demographic components used in
EJScreen's EJ index calculations.

Args:
    state: Two-letter US state abbreviation (e.g. 'WA', 'CA').
    county_fips: Optional county FIPS code (3-digit or 5-digit).
                 If omitted, returns state-level results sorted by
                 highest demographic index.
    limit: Maximum number of block groups to return (default 50, max 500).

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": {
      "state": "<state>"
    },
    "name": "get_demographic_indicators"
  }
}

Input Schema

Name	Required	Description	Default
`limit`	No
`state`	Yes
`county_fips`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedApr 3, 2026

TDQS

A4.3/5.0

Behavior4/5

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

With no annotations, the description carries the burden and does well: it discloses the data types returned (minority %, low income %, linguistic isolation, education, age), the default limit of 50 with max 500, and the state-level behavior when county_fips is omitted. While it doesn't discuss error cases or performance, the core behavior is transparent.

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?

The description is well-structured with a clear first sentence, a concise list of data contents, and a compact Args section that covers all parameters. It is appropriately sized and front-loaded, though the Args block could arguably be tightened without losing clarity.

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?

Given the tool's moderate complexity (3 params, output schema present), the description is complete enough: it specifies the primary behavior, the data categories, and parameter semantics. The output schema likely covers return shape, so not explaining return structure is acceptable. Missing explicit alternatives is the only gap.

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?

Although the input schema provides no descriptions (0% coverage), the description compensates by explaining each parameter: state format with examples, county_fips format and optionality, and limit default/max. This adds meaning beyond the schema and helps the agent construct correct calls.

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 uses a specific verb ('Get') and resource ('demographic vulnerability indicators by block group'), clearly distinguishing it from sibling tools like get_environmental_indicators or get_ej_county_summary. It also ties the tool to EJScreen's EJ index calculations, providing unique scope.

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: returns demographic indicators, can be limited to a county or state-level when county_fips is omitted, and sorted by highest demographic index. It does not explicitly state when to use this over alternatives, but the context is sufficient for an agent to infer appropriate usage.

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

All EPA EJScreen tools Inspect

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