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What is the sales tax rate at this US address, ZIP+4 or ZIP? The combined rate and each state, county, city and district rate in the 24 Streamlined Sales Tax states (WA, OH, MI, NJ, TN, …), computed by Distill from each state’s SST rate and boundary files

tax_sales_rate
Read-only

What is the sales tax rate at this US address, ZIP+4 or ZIP? The combined rate and each state, county, city and district rate in the 24 Streamlined Sales Tax states (WA, OH, MI, NJ, TN, …), computed by Distill from each state’s SST rate and boundary files. From the state’s own Streamlined Sales Tax rate and boundary files (24 states: AR, GA, IA, IN, KS, KY, MI, MN, NC, ND, NE, NJ, NV, OH, OK, RI, SD, TN, UT, VT, WA, WI, WV, WY). Matches an address when the state publishes address records, else the ZIP+4 record, else the 5-digit record (the lowest rate in the ZIP, per SSUTA 305). Returns each jurisdiction’s rate, the combined rate, and the period it holds, for any sale date from the first day of the previous quarter on (default today). Locations outside these states answer 404 and are not charged. Refreshed quarterly (live freshness: /status). Price: $0.005 per call. Free tier: 3 free calls a day per IP, at most 3 rows per answer, taken by an unpaid call unless its _meta["distill/free-tier"] is "skip". Answers in a summary view of about 3,000 tokens; view: "full" for every row. Confidence: agreement × freshness. Agreement: for a 5-digit ZIP answer, the share of that ZIP’s ZIP+4 records with the same combined rate; for a ZIP+4 answer, the share of address records inside it with the same rate; 1 for an address match or when the state publishes nothing finer. Freshness: 1 until the next SST posting deadline (the 1st of Mar, Jun, Sep or Dec) after the files were last checked, then halving every 30 days. Not tax advice. Rates as published by the state in its Streamlined Sales Tax rate and boundary files for the stated effective period; verify with the state. See /terms.

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": {
      "zip": "<zip>"
    },
    "name": "tax_sales_rate"
  }
}

Input Schema

NameRequiredDescriptionDefault
zipYesA 5-digit ZIP code or a ZIP+4 (98101-3143 or 981013143).
dateNoThe sale date, YYYY-MM-DD (default: today, UTC). From the first day of the previous quarter onward.
viewNosummary (the default): the answer a model needs, budgeted; full: every row (a free answer stays capped).
addressNoOptional street address line with house number, e.g. "1010 E Alder St" or "PO Box 12"; matched against the state address records when it publishes them.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • addedInput schema / properties / view
      Added value: +{
      +  "description": "summary (the default): the answer a model needs, budgeted; full: every row (a free answer stays capped).",
      +  "enum": [
      +    "summary",
      +    "full"
      +  ],
      +  "type": "string"
      +}
  2. First observed

TDQS

A4.5/5.0
Behavior5/5

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

Annotations only say readOnly and closed-world; the description adds substantial behavior the annotations cannot carry — price per call ($0.005), free-tier accounting (3/day per IP, 3-row cap, _meta skip flag), 404-not-charged semantics, quarterly refresh with a /status pointer, and the confidence formula (agreement × freshness with halving every 30 days). This is far beyond the structured fields.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The lead question is well front-loaded, but the remainder is a dense run-on stacking pricing, free-tier rules, matching precedence, confidence math, and disclaimers with no breaks. Nearly every sentence carries information, yet the reader must parse a wall of text to extract the invocation-relevant parts.

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?

With no output schema, the description still discloses the return shape (each jurisdiction's rate, combined rate, and effective period), the size budget (~3,000 tokens vs full), error behavior (404), freshness, and confidence interpretation. For a paid, rate-limited lookup tool, nothing material needed to invoke or interpret it is missing.

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 is 3, but the description genuinely adds meaning: the address → ZIP+4 → 5-digit fallback hierarchy and the SSUTA 305 'lowest rate in the ZIP' rule, plus the ~3,000-token budget for summary versus every row for full. The date window constraint is also restated usefully; only minor format detail (YYYY-MM-DD) is left entirely to 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?

The description opens with the exact question answered — "What is the sales tax rate at this US address, ZIP+4 or ZIP?" — and specifies the output decomposition (state, county, city, district plus combined rate) and the coverage universe (24 SST states). An agent can tell this is a single-location lookup, distinct from tax_sales_rate_batch, 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?

It states clear operating conditions: sale dates from the first day of the previous quarter onward (default today), and that locations outside the 24 states return 404 and are not charged (i.e., do not use for non-SST addresses). It does not explicitly route between the default summary view and batch/alternative tools, so an explicit 'use tax_sales_rate_batch instead when…' is missing.

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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