Profullstack

NicheDB: Population Lookup

nichedb_population

Read-onlyIdempotent

[NicheDB] Population and demography, drilled down from the world to the ZIP code. Give a key (us, us-ca, us-ca-los-angeles, gb, gb-england-london), a US zip, or a place name in q; no argument is the world. Answers with the area (population, year, measures: age, income, home value, rent, poverty, education, unemployment, race and Hispanic origin for the US; growth, age structure, births, deaths, fertility, life expectancy, migration, GDP per head and Gini for countries), how many areas of each level it contains, and the largest of its children at level (country, state, city or zip). Sources: World Bank, US Census ACS 5-year, GeoNames.

Served by NicheDB (https://nichedb.dev/docs/mcp).

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "nichedb_population"
  }
}

Input Schema

Name	Required	Description
`q`	No	A place name to look up, e.g. Springfield (optional)
`key`	No	Area key, e.g. us, us-ca, us-ca-los-angeles, us-90210, de (optional)
`zip`	No	A US ZIP code (optional), 5 digits, e.g. 90210
`level`	No	Which children to list: country, state, city or zip (optional)
`limit`	No	Children to list, default 20, max 500
`offset`	No	Skip this many children, for paging

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 11, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so safety is covered. The description adds real value on the data side: the exact measure sets for US areas versus countries, that results include per-level child counts and the largest children at `level`, and the underlying sources (World Bank, ACS 5-year, GeoNames).

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?

Purpose and accepted selectors are front-loaded, and the trailing parenthetical measure lists are dense but genuinely informative for deciding whether to call it. The paragraph is long and the nested parentheses make it slightly harder to scan than a bulleted measure list would be.

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?

For a six-parameter, optional-only lookup with no output schema, the definition covers inputs, defaults, returned content, and provenance. It does not describe pagination behavior for the child list (limit/offset) or the response shape, but those gaps are minor given the 100% 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%, so the baseline is 3, but the description goes beyond it by showing the key hierarchy concretely (us, us-ca, us-ca-los-angeles, gb, gb-england-london) and by stating the default behavior when no argument is supplied, which the schema does not express.

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 specific verb and resource ('Population and demography, drilled down from the world to the ZIP code') and enumerates the accepted selectors (key, zip, q) plus the no-argument default. The domain is unambiguous against siblings like nichedb_transit_city or nichedb_satellite_lookup, which cover entirely different subjects.

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?

Explains how to invoke it: pass a hierarchical `key`, a 5-digit US `zip`, or a place name in `q`, and that no argument returns the world. That is clear invocation context but there is no when-not-to-use guidance or pointer to an alternative tool for related lookups.

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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