{"openapi":"3.1.0","info":{"title":"Salestax API","version":"0.1.0","description":"A US sales-tax calculator bundling real state and average combined sales-tax rates (Tax Foundation, midyear 2026): tax and total on a purchase, state and average-combined rate lookup, multi-state comparison, no-sales-tax states, reverse (tax-inclusive) calculation, a multi-item cart total with per-item exemptions, general exemption-category notes, a full state ranking and a glossary. Local rates vary by address; every figure says so.\n\nEvery operation is read-only or compute-only. The same tools are available over MCP (streamable HTTP) at https://salestax.connectorbay.com/mcp.","contact":{"name":"Unify Dynamics LLC","email":"hr@unifydynamics.com","url":"https://connectorbay.com/salestax/docs"},"termsOfService":"https://connectorbay.com/salestax/terms"},"servers":[{"url":"https://salestax.connectorbay.com"}],"externalDocs":{"url":"https://connectorbay.com/salestax/docs"},"security":[{},{"bearer":[]}],"components":{"securitySchemes":{"bearer":{"type":"http","scheme":"bearer","description":"Optional. A Pro API key raises rate limits; no credentials are required."}},"schemas":{"Error":{"type":"object","properties":{"ok":{"const":false},"error":{"type":"object"}}}}},"paths":{"/v1/tools/calculate_tax":{"post":{"operationId":"calculate_tax","summary":"Computes the approximate sales tax and total for a purchase in a US state, using either your supplied local","description":"Computes the approximate sales tax and total for a purchase in a US state, using either your supplied local\n    rate for a specific address or the state's average combined rate as an approximation. Use for \"sales tax on\n    $500 in California\", \"tax on a $50 purchase in Denver, Colorado at an 8.81% combined rate\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"state":{"description":"A US state name, abbreviation, or DC.","examples":["California","CA","Texas"],"minLength":2,"title":"State","type":"string"},"amount":{"description":"Purchase amount before tax.","examples":[500],"minimum":0,"title":"Amount","type":"number"},"local_rate_pct":{"anyOf":[{"maximum":15,"minimum":0,"type":"number"},{"type":"null"}],"default":null,"description":"A specific local (city/county) rate to add to the state rate, if you know it. Omit to use the state's average combined rate.","title":"Local Rate Pct"}},"required":["state","amount"],"title":"calculate_taxArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/state_rate":{"post":{"operationId":"state_rate","summary":"A state's statewide (base) sales-tax rate, average local rate and average combined rate. Use for \"what's","description":"A state's statewide (base) sales-tax rate, average local rate and average combined rate. Use for \"what's\n    the sales tax rate in Texas\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"state":{"description":"A US state name, abbreviation, or DC.","minLength":2,"title":"State","type":"string"}},"required":["state"],"title":"state_rateArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/average_combined_rate":{"post":{"operationId":"average_combined_rate","summary":"A state's average combined (state + local) sales-tax rate, explicitly framed as a population-weighted","description":"A state's average combined (state + local) sales-tax rate, explicitly framed as a population-weighted\n    average approximation, not the rate at any one address. Use for \"what's the average combined sales tax rate in\n    Illinois\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"state":{"description":"A US state name, abbreviation, or DC.","minLength":2,"title":"State","type":"string"}},"required":["state"],"title":"average_combined_rateArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/compare_states":{"post":{"operationId":"compare_states","summary":"Compares sales tax on the same purchase amount across several states, using each state's average combined","description":"Compares sales tax on the same purchase amount across several states, using each state's average combined\n    rate, ranked cheapest to most expensive. Use for \"compare sales tax in Texas, Oregon and New York for a $1,000\n    purchase\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"states":{"description":"2-20 state names/abbreviations to compare.","items":{"type":"string"},"maxItems":20,"minItems":2,"title":"States","type":"array"},"amount":{"description":"Purchase amount to compare tax on.","examples":[1000],"minimum":0,"title":"Amount","type":"number"}},"required":["states","amount"],"title":"compare_statesArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/no_sales_tax_states":{"post":{"operationId":"no_sales_tax_states","summary":"The states with no statewide sales tax (Alaska, Delaware, Montana, New Hampshire, Oregon), noting that","description":"The states with no statewide sales tax (Alaska, Delaware, Montana, New Hampshire, Oregon), noting that\n    Alaska still allows local sales taxes in many municipalities. Use for \"what states have no sales tax\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{},"title":"no_sales_tax_statesArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/reverse_calculate":{"post":{"operationId":"reverse_calculate","summary":"Backs out the pre-tax price and the tax amount from a tax-inclusive total at a known rate. Use for \"if $118","description":"Backs out the pre-tax price and the tax amount from a tax-inclusive total at a known rate. Use for \"if $118\n    already includes 8% tax, what was the price before tax\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"total_amount":{"description":"A tax-inclusive total.","examples":[118],"minimum":0,"title":"Total Amount","type":"number"},"rate_pct":{"description":"The combined tax rate that was applied.","examples":[8],"maximum":20,"minimum":0,"title":"Rate Pct","type":"number"}},"required":["total_amount","rate_pct"],"title":"reverse_calculateArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/multi_item_total":{"post":{"operationId":"multi_item_total","summary":"Totals a cart applying tax only to items marked taxable (mark exempt items like groceries, where applicable","description":"Totals a cart applying tax only to items marked taxable (mark exempt items like groceries, where applicable\n    in your state, as \"taxable\": false). Use for \"total my cart with tax in New York, groceries are exempt\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"items":{"description":"1-100 items, each {\"name\": \"...\", \"price\": 9.99, \"quantity\": 1, \"taxable\": true}. taxable defaults to true.","items":{"additionalProperties":true,"type":"object"},"title":"Items","type":"array"},"state":{"description":"A US state name or abbreviation.","minLength":2,"title":"State","type":"string"},"local_rate_pct":{"anyOf":[{"maximum":15,"minimum":0,"type":"number"},{"type":"null"}],"default":null,"description":"A specific local rate, if known. Omit for the state's average combined rate.","title":"Local Rate Pct"}},"required":["items","state"],"title":"multi_item_totalArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/exemption_note":{"post":{"operationId":"exemption_note","summary":"General categories commonly exempted or taxed at a reduced rate SOMEWHERE in the US (groceries,","description":"General categories commonly exempted or taxed at a reduced rate SOMEWHERE in the US (groceries,\n    prescription drugs, clothing, digital goods) — a general pattern across states, not a definitive per-state\n    exemption database. Use for \"are groceries taxed\", \"is clothing exempt from sales tax\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{},"title":"exemption_noteArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/states_list":{"post":{"operationId":"states_list","summary":"All 50 states plus DC with their statewide, average local and average combined sales-tax rates, ranked","description":"All 50 states plus DC with their statewide, average local and average combined sales-tax rates, ranked\n    highest combined rate to lowest. Use for \"which state has the highest sales tax\", \"rank states by sales tax\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{},"title":"states_listArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/glossary":{"post":{"operationId":"glossary","summary":"Definitions of sales-tax terms — nexus, use tax, combined rate, origin/destination-based sourcing, special","description":"Definitions of sales-tax terms — nexus, use tax, combined rate, origin/destination-based sourcing, special\n    district, sales tax holiday. Use for \"what's nexus\", \"what's a use tax\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"term":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"A specific term to look up; omit to list all.","title":"Term"}},"title":"glossaryArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}}}}