Assert an agent’s output

Paste an output, pick a rubric or write the checks, and assert runs them: JSON schema, required or banned terms, lengths, citations present, quotations found verbatim in a source. Every check is a pure function of the inputs, so the same output gets the same verdict every time, and the answer is a signed Assay record that names which check failed and where. This page calls api.s2ar.dev from your browser on today’s free samples (three a day, up to 4,000 characters) or on your own key; after the samples, the answer is the 402 quote an agent would pay, with the ways to pay it.

Rubric
Output

Source (for quotes_in_source)

Checks (JSON, used when no rubric is picked)

An agent calls the same route with GET https://api.s2ar.dev/v1/assert?text=…&checks=… or a POST, or the assert_output tool over MCP. The worked version is Assert an agent’s output; the chained one is An agent’s day.