census-mcp-server

Resolve Census Geography

census_resolve_geography

Read-only

Resolve a place name, ZIP code, or street address to Census FIPS identifiers. Converts names like "King County, WA", "Seattle, WA", or "Seattle-Tacoma-Bellevue, WA", and ZIPs like "98109", to the codes required by census_query_data and census_compare_geographies. Use before querying when you have a place name rather than raw FIPS codes — state_fips maps to parent_fips and fips_summary maps to geography_fips in downstream tools, and geography_type is itself the geography_level to query at.

Input Schema

TableJSON Schema

Name	Required	Description
`name`	Yes	Place name (e.g., "King County, WA", "Seattle, WA", "California"), 5-digit ZIP code (e.g., "98109", resolved to its ZIP Code Tabulation Area), or street address (e.g., "1600 Pennsylvania Ave NW, Washington, DC 20500"). Include the state after a comma — its abbreviation or full name, as in "Chatham County, Georgia" — to disambiguate places with common names. It narrows a statistical area as well, matching any state the area spans, so "Kansas City, MO" and "Kansas City, KS" both reach the MO-KS metro area. Matching ignores case, reads "Saint" and "St." as the same word, and accepts unaccented spellings ("Dona Ana County, NM"). For a statistical area a leading city is enough ("Denver, CO" for the Denver-Aurora-Centennial metro area), and an older full name resolves through its leading city ("Denver-Aurora-Lakewood, CO").
`county_fips`	No	County FIPS code to resolve within — 1 to 3 digits, zero-padded here to the 3 the Census stores. A tract name is unique only inside its county, so a bare tract name matching two counties comes back as ambiguous_name until this is set: take the countyFips of the candidate you want from that error and re-call. Only county and tract sit within a county, so this restricts resolution to those two levels — pairing it with any other geography_type, or with a street address, is a county_scope_unsupported error rather than a scope quietly dropped. census_query_data takes the same code as its own county_fips but pads nothing, so hand it the 3-digit county_fips returned here, not the shorter value.
`geography_type`	No	Geography level to resolve to, named exactly as census_query_data's geography_level and census_list_geographies name it. Auto-detection covers only state, county, place, tract, and zip code tabulation area: zip code tabulation area for a 5-digit ZIP or ZIP+4 — the ACS's ZIP-shaped area, not cbp's "zip code" level, which takes the ZIP itself with no resolution — state for a two-letter abbreviation or a spelled-out state name, county when the name contains the word "County" or "Parish", county then place for the word "Borough" (an Alaska borough is a county, a PA or NJ borough a place), tract for the word "Tract", otherwise place (incorporated places and census-designated places together) with a fallback to county, where a census-designated place answers only when no incorporated place or county has the exact name — "Arlington, VA" is Arlington County, and set "place" to reach the Arlington CDP. The other four are never auto-detected and must be set explicitly, because their names overlap city names — "metropolitan statistical area/micropolitan statistical area" covers both metro and micro areas and yields a 5-digit code, "combined statistical area" yields a 3-digit code, "consolidated city" covers the eight merged city-county governments (Nashville-Davidson, Louisville/Jefferson County, Indianapolis, Athens-Clarke County, Augusta-Richmond County, Butte-Silver Bow, Milford CT, Greeley County KS), and "economic place" yields the 8-digit code ecnbasic 2022 publishes a place under: the 3-digit county it lies in (000 when it spans counties) followed by its 5-digit place code. Economic places are the incorporated places, census-designated places, and county subdivisions the 2022 Economic Census tabulates, plus each county's remainder ("Balance of Adams County, WA"). Setting it explicitly also overrides auto-detection — "New York" auto-detects as the state, so New York City needs "place".

Output Schema

TableJSON Schema

Name	Required	Description
`name`	No	Canonical name of the resolved geography.
`error`	No	Present when the call failed. Absent on success.
`place_fips`	No	5-digit place FIPS code when the resolved geography is a place — incorporated or census-designated. For an economic place, the place part of its 8-digit code, which is also the place code the 2017 and 2012 ecnbasic vintages take. For a street address, the incorporated place the address sits in (query it at the place level with state_fips as parent_fips); absent when the address is outside every incorporated place, and a census-designated place is never reported for an address.
`state_fips`	No	2-digit state FIPS code. Use as parent_fips in census_query_data for sub-state queries. Absent for a metropolitan/micropolitan or combined statistical area, which can span several states and needs no parent_fips, and for a zip code tabulation area, whose source layer carries no state.
`tract_fips`	No	6-digit census tract FIPS code when the resolved geography is a tract — from a street address, or from a tract name.
`county_fips`	No	3-digit county FIPS code when the resolved geography is a county or sub-county level.
`fips_summary`	No	Pre-formatted FIPS value ready to use as geography_fips in census_query_data (e.g., "033" for King County with state_fips "53" as parent_fips, "42660" for the Seattle-Tacoma-Bellevue metro area with no parent at all, "03363000" for Seattle as an ecnbasic 2022 economic place).
`geography_type`	No	Resolved geography level. Pass this straight through as geography_level in census_query_data and census_compare_geographies.
`block_group_fips`	No	1-digit block group within tract_fips, for a street address only. Query it as geography_level "block group" with this as geography_fips, alongside parent_fips, county_fips, and tract_fips. geography_type and fips_summary stay at the tract.
`census_designated_place`	No	Present (true) when the resolved place or economic place is a census-designated place (CDP): an unincorporated community the Census delineates for statistics, with no municipal government. Its code is queried like an incorporated place's. Absent for an incorporated place and every other level.

Schema Changelog

Changes observed during successful MCP inspections.

Changed8 schema fields changedSep 25, 2026

changedInput schema / properties / geography_type / description

Previous value: -"Geography level to resolve to, named exactly as census_query_data's geography_level and census_list_geographies name it. Auto-detection covers only state, county, place, and tract: state for a two-letter abbreviation or a spelled-out state name, county when the name contains \"County\"/\"Borough\"/\"Parish\", tract when it contains \"Tract\", otherwise place with a fallback to county. The other three are never auto-detected and must be set explicitly, because their names overlap city names — \"metropolitan statistical area/micropolitan statistical area\" covers both metro and micro areas and yields a 5-digit code, \"combined statistical area\" yields a 3-digit code, and \"consolidated city\" covers the eight merged city-county governments (Nashville-Davidson, Louisville/Jefferson County, Indianapolis, Athens-Clarke County, Augusta-Richmond County, Butte-Silver Bow, Milford CT, Greeley County KS). Setting it explicitly also overrides auto-detection — \"New York\" auto-detects as the state, so New York City needs \"place\"."New value: +"Geography level to resolve to, named exactly as census_query_data's geography_level and census_list_geographies name it. Auto-detection covers only state, county, place, tract, and zip code tabulation area: zip code tabulation area for a 5-digit ZIP or ZIP+4 — the ACS's ZIP-shaped area, not cbp's \"zip code\" level, which takes the ZIP itself with no resolution — state for a two-letter abbreviation or a spelled-out state name, county when the name contains the word \"County\" or \"Parish\", county then place for the word \"Borough\" (an Alaska borough is a county, a PA or NJ borough a place), tract for the word \"Tract\", otherwise place (incorporated places and census-designated places together) with a fallback to county, where a census-designated place answers only when no incorporated place or county has the exact name — \"Arlington, VA\" is Arlington County, and set \"place\" to reach the Arlington CDP. The other four are never auto-detected and must be set explicitly, because their names overlap city names — \"metropolitan statistical area/micropolitan statistical area\" covers both metro and micro areas and yields a 5-digit code, \"combined statistical area\" yields a 3-digit code, \"consolidated city\" covers the eight merged city-county governments (Nashville-Davidson, Louisville/Jefferson County, Indianapolis, Athens-Clarke County, Augusta-Richmond County, Butte-Silver Bow, Milford CT, Greeley County KS), and \"economic place\" yields the 8-digit code ecnbasic 2022 publishes a place under: the 3-digit county it lies in (000 when it spans counties) followed by its 5-digit place code. Economic places are the incorporated places, census-designated places, and county subdivisions the 2022 Economic Census tabulates, plus each county's remainder (\"Balance of Adams County, WA\"). Setting it explicitly also overrides auto-detection — \"New York\" auto-detects as the state, so New York City needs \"place\"."

changedInput schema / properties / geography_type / enum

Previous value: -[
-  "state",
-  "county",
-  "place",
-  "tract",
-  "metropolitan statistical area/micropolitan statistical area",
-  "combined statistical area",
-  "consolidated city"
-]New value: +[
+  "state",
+  "county",
+  "place",
+  "tract",
+  "metropolitan statistical area/micropolitan statistical area",
+  "combined statistical area",
+  "consolidated city",
+  "zip code tabulation area",
+  "economic place"
+]

changedInput schema / properties / name / description

Previous value: -"Place name (e.g., \"King County, WA\", \"Seattle, WA\", \"California\") or street address (e.g., \"1600 Pennsylvania Ave NW, Washington, DC 20500\"). Include the state abbreviation to disambiguate places with common names — it narrows a statistical area as well, matching any state the area spans, so \"Kansas City, MO\" and \"Kansas City, KS\" both reach the MO-KS metro area. For a statistical area, the name is the full hyphenated one the Census publishes (\"Seattle-Tacoma-Bellevue, WA\" for the metro area, \"Seattle-Tacoma, WA\" for the combined one) — a single city name matches it too when only one area contains that city."New value: +"Place name (e.g., \"King County, WA\", \"Seattle, WA\", \"California\"), 5-digit ZIP code (e.g., \"98109\", resolved to its ZIP Code Tabulation Area), or street address (e.g., \"1600 Pennsylvania Ave NW, Washington, DC 20500\"). Include the state after a comma — its abbreviation or full name, as in \"Chatham County, Georgia\" — to disambiguate places with common names. It narrows a statistical area as well, matching any state the area spans, so \"Kansas City, MO\" and \"Kansas City, KS\" both reach the MO-KS metro area. Matching ignores case, reads \"Saint\" and \"St.\" as the same word, and accepts unaccented spellings (\"Dona Ana County, NM\"). For a statistical area a leading city is enough (\"Denver, CO\" for the Denver-Aurora-Centennial metro area), and an older full name resolves through its leading city (\"Denver-Aurora-Lakewood, CO\")."

addedOutput schema / properties / block_group_fips

Added value: +{
+  "description": "1-digit block group within tract_fips, for a street address only. Query it as geography_level \"block group\" with this as geography_fips, alongside parent_fips, county_fips, and tract_fips. geography_type and fips_summary stay at the tract.",
+  "type": "string"
+}

addedOutput schema / properties / census_designated_place

Added value: +{
+  "const": true,
+  "description": "Present (true) when the resolved place or economic place is a census-designated place (CDP): an unincorporated community the Census delineates for statistics, with no municipal government. Its code is queried like an incorporated place's. Absent for an incorporated place and every other level.",
+  "type": "boolean"
+}

changedOutput schema / properties / fips_summary / description

Previous value: -"Pre-formatted FIPS value ready to use as geography_fips in census_query_data (e.g., \"033\" for King County with state_fips \"53\" as parent_fips, \"42660\" for the Seattle-Tacoma-Bellevue metro area with no parent at all)."New value: +"Pre-formatted FIPS value ready to use as geography_fips in census_query_data (e.g., \"033\" for King County with state_fips \"53\" as parent_fips, \"42660\" for the Seattle-Tacoma-Bellevue metro area with no parent at all, \"03363000\" for Seattle as an ecnbasic 2022 economic place)."

changedOutput schema / properties / place_fips / description

Previous value: -"Place FIPS code when the resolved geography is an incorporated place."New value: +"5-digit place FIPS code when the resolved geography is a place — incorporated or census-designated. For an economic place, the place part of its 8-digit code, which is also the place code the 2017 and 2012 ecnbasic vintages take. For a street address, the incorporated place the address sits in (query it at the place level with state_fips as parent_fips); absent when the address is outside every incorporated place, and a census-designated place is never reported for an address."

changedOutput schema / properties / state_fips / description

Previous value: -"2-digit state FIPS code. Use as parent_fips in census_query_data for sub-state queries. Absent for a metropolitan/micropolitan or combined statistical area, which can span several states and needs no parent_fips."New value: +"2-digit state FIPS code. Use as parent_fips in census_query_data for sub-state queries. Absent for a metropolitan/micropolitan or combined statistical area, which can span several states and needs no parent_fips, and for a zip code tabulation area, whose source layer carries no state."

First observedSep 19, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Beyond the readOnlyHint annotation, the description discloses detailed matching behavior: case-insensitivity, 'Saint'/'St.' equivalence, unaccented spellings, auto-detection coverage for specific geography types, explicit override behavior, and error conditions like ambiguous_name and county_scope_unsupported. It also mentions county_fips zero-padding and how to pass the value to census_query_data, adding substantial behavioral 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?

The description is three sentences, each earning its place: the first states the core purpose with examples, the second gives the usage context and mapping, and the third reinforces the downstream connection. No filler or redundant restating of the title or schema.

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

Completeness5/5

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

Given the tool's complexity (auto-detection rules, multiple geography types, error states, downstream mapping), the description covers all essential selection and invocation information. The existence of an output schema means the return structure does not need to be spelled out here, and the annotations plus description suffice for safe, correct calling.

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 description coverage is 100%, so the baseline is 3. The tool description adds value by explaining how the resolved outputs map to downstream parameters (state_fips→parent_fips, fips_summary→geography_fips, geography_type→geography_level), which is not present in the parameter schemas. This enriches the medication of the parameters' purpose in the broader workflow.

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 opens with a specific verb and resource: 'Resolve a place name, ZIP code, or street address to Census FIPS identifiers.' It gives concrete examples and explicitly ties the output to downstream tools (census_query_data, census_compare_geographies), distinguishing this from siblings by stating it converts names to codes rather than querying data directly.

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

Usage Guidelines5/5

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

The description states exactly when to use the tool: 'Use before querying when you have a place name rather than raw FIPS codes.' It also explains how the output maps to parameters of downstream tools (state_fips→parent_fips, fips_summary→geography_fips, geography_type→geography_level), giving clear routing guidance without needing to inspect sibling schemas.

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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