Agent connection guide
TaxKit offers tools for discovering calculators, checking their input fields, running a calculation and reading documentation. They use the same calculator and documentation services as the website and HTTP API. No TaxKit account or API key is required.
Connect a remote AI app
- Open your app's MCP server settings. MCP lets an AI app call tools offered by another service.
- Add a server called TaxKit, using Streamable HTTP.
- Enter
https://api.taxkit.dev/mcpas its address. - Let the app discover the tools, then ask it to list the supported calculators.
- Read the chosen calculator's input fields before sending any figures. Check the returned tax year, assumptions, breakdown and sources with the answer.
For a preview or your own installation, use the address shown on that website's For agents page. Keep the website and API in the same environment.
The endpoint offers protocol versions 2026-07-28 and 2025-11-25. The newer
version sends its version and method information on each request. The older
version first starts a conversation and then sends its session ID. Let your
client handle those headers and messages; changing the version label alone does
not change the protocol. Other versions are refused.
Remote tools
| Tool | Use |
|---|---|
taxkit_list_calculators | Find supported calculators and their facts. |
taxkit_get_calculator_schema | Read the selected calculator's input fields, outputs, rules and sources. |
taxkit_calculate | Send checked facts and read the returned report. |
taxkit_docs_navigation | Find the accepted public documentation pages. |
taxkit_find_docs | Search those pages with up to 100 characters. |
taxkit_read_doc | Read a discovered page, including its processed Markdown. |
Use the tool's discovered input definition rather than guessing field names or units. Calculation inputs are checked. TaxKit does not save personal reports or repeat a failed calculation automatically.
Browser tools
WebMCP is an experimental browser feature.
TaxKit detects support when a calculator is open. A supporting browser agent can
use taxkit_find_calculators, taxkit_read_calculator,
taxkit_fill_calculator, taxkit_calculate_visible_form and
taxkit_read_result on that page.
Filling the form changes the fields you can see. Calculating presses the same Calculate command as manual use. Editing a field stops unfinished browser work and marks the old answer out of date. Read the waiting state, message and out-of-date marker before using an answer. Leaving the calculator removes its tools and stops its unfinished browser work.
TaxKit's tests exercise native tool calls in Chromium 153 with WebMCP enabled. That does not mean every browser or AI app supports these tools. Ordinary browsers keep the usual forms and buttons. A remote MCP connection does not provide control of the browser page.
Limits and failed calls
- Calculations use the existing anonymous allowance: 60 calls per 60 seconds. Cloudflare applies it approximately at each location; it is not a global quota. Each application instance admits up to eight calculations without queuing.
- A calculation has a five-second work limit. POST bodies are limited to 64 KiB and five seconds to read. Complete MCP replies are limited to 2 MiB and ten seconds.
- Modern remote cancellation stops the client. On the tested Worker runtime, server calculation work can continue until its five-second limit. Prompt server cleanup before the reply starts is not guaranteed.
- An older client's cancellation notification stops only its own conversation's call and releases that calculation's place. Older conversations share a host with at most 32 initialisation attempts and 32 concurrent requests during its ten-minute lifetime. A late connection has only the remaining time. Expiry or host eviction returns 404; start a fresh conversation.
- Calls without an Origin header are accepted. Browser calls must use this installation's configured website origin; other supplied origins are refused. This is a browser origin check, not a login system.
- When a call is refused or times out, read its fixed error code and guidance. Retry only after checking the cause. Subscriptions, resumed streams and saved conversations across host eviction are not offered.
The annual income-tax calculator's Medicare thresholds are awaiting correction. Its answer may overstate the levy for some lower incomes. Take-home pay and PAYG withholding use separate rules. See the calculator's supported year and sources.
Read documentation without tools
Accepted documentation pages have a Read as Markdown link. The website's
/llms.txt lists accepted pages and /llms-full.txt includes their processed
bodies. These files contain documentation, not your calculation reports.
For ordinary HTTP integration, use API overview, OpenAPI reference and Endpoints.