Cook County / Chicago Property Data (free tier, no wallet needed)

Cook County parcel record (100 free a day)

get_cook_county_parcel

Read-onlyIdempotent

FREE for your first 100 calls each day — no wallet, no signup, just call it ($0.01 per call via x402/USDC only after that daily allowance, which resets at 00:00 UTC). Cook County, IL parcel record for a 10- or 14-digit PIN. Returns: pin, prop_address, prop_city, prop_zip, class, township_name, nbhd_code, municipality, ward, police_district, census_tract_geoid, school_elementary_district, school_secondary_district, walk_score_cmap, airport_noise_dnl, lat, lon, tax_year. The cheap single-property lookup — use get_cook_county_property_dossier for sales, permits and assessments.

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": {
      "pin": "<pin>"
    },
    "name": "get_cook_county_parcel"
  }
}

Input Schema

Name	Required	Description	Default
`pin`	Yes	10- or 14-digit Cook County PIN (digits; dashes allowed, e.g. 09-25-306-051-0000). If you only have a street address, call search_chicago_property_by_address first.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 16, 2026

changedInput schema / properties / pin / description

Previous value: -"10- or 14-digit Cook County PIN (digits; dashes allowed, e.g. 14-08-120-017-0000). If you only have a street address, call search_chicago_property_by_address first."New value: +"10- or 14-digit Cook County PIN (digits; dashes allowed, e.g. 09-25-306-051-0000). If you only have a street address, call search_chicago_property_by_address first."

Changed1 schema field changedJul 16, 2026
- changedInput schema / properties / pin / pattern
```
Previous value: -"^[0-9][0-9\\-]{8,17}$"New value: +"^[0-9][0-9\\-]{8,19}$"
```

Changed2 schema fields changedJul 12, 2026

addedInput schema / properties / pin / description

Added value: +"10- or 14-digit Cook County PIN (digits; dashes allowed, e.g. 14-08-120-017-0000). If you only have a street address, call search_chicago_property_by_address first."

addedInput schema / properties / pin / pattern
```
Added value: +"^[0-9][0-9\\-]{8,17}$"
```

First observedJun 28, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already cover read-only, idempotency, open-world and non-destructive semantics, so the description is not obligated to restate safety. It adds genuinely new behavioral context not present in structured fields: the free-100-calls-per-day allowance, $0.01 x402/USDC pricing after that, and the UTC reset window. It stops short of describing failure behavior for malformed PINs or unknown parcels, keeping it below a 5.

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?

Front-loads the pricing/commercial constraint, then the resource definition, then the return fields, then the sibling routing — a sensible ordering. The enumerated return-field list is long but earns its place because there is no output schema; only minor trimming is possible.

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 no output schema, the description compensates by enumerating the returned fields (pin, prop_address, class, lat/lon, tax_year, etc.), and it covers geographic scope, PIN format via the schema, pricing, and alternatives. It is close to complete for a simple single-parameter lookup; the only gap is error/empty-result behavior.

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% and the single pin parameter already carries a regex pattern, an accepted format example, and the address-lookup fallback, so the schema does the heavy lifting and the baseline is 3. The description only restates '10- or 14-digit PIN' and does not add format or validation detail beyond the schema.

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+resource+scope: 'Cook County, IL parcel record for a 10- or 14-digit PIN.' It explicitly differentiates itself from the sibling get_cook_county_property_dossier (sales/permits/assessments) and from search_chicago_property_by_address (address-only entry path), so an agent can route without opening any schema.

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?

Explicitly positions itself as 'the cheap single-property lookup' and names the alternative plus the condition that selects it: get_cook_county_property_dossier 'for sales, permits and assessments.' It also states the free-tier boundary and when paid billing kicks in (after 100 calls/day, reset 00:00 UTC), which is decision-relevant.

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

All Cook County / Chicago Property Data (free tier, no wallet needed) tools Inspect

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