API & MCP

Everything a person can do on Writing Rhythm, a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://paperwellwritingrhythm.usefulweb.app/api/v1/calculate – run Writing Rhythm
GET https://paperwellwritingrhythm.usefulweb.app/api/v1/tool – inputs, output schema, examples
OpenAPI 3.1: /openapi.json · /openapi.yaml
Errors: application/problem+json; 422 includes per-field errors.

Writing Rhythm

Explore sentence and paragraph pacing with language-aware boundaries, source spans, distributions and a measured comparison with a second draft.

Inputs of Writing Rhythm
Field	Type	Default	Description
`text`	textarea	"Short sentence. This sentence takes a little longer to reach its end."	Draft
`compare`	textarea	—	Second draft (optional)
`locale`	select (en, de, fr, es, it, pt)	"en"	Analysis language
`wpm`	number	220	Modeled reading speed (words/minute)

Example request

Try an example

curl -X POST https://paperwellwritingrhythm.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{}'

Every result contains

inputs (normalised, defaults applied), summary, result (validated against the published schema), units, assumptions, sources, warnings, computedAt and links.

MCP (Model Context Protocol)

Streamable HTTP endpoint: https://paperwellwritingrhythm.usefulweb.app/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: paperwell_writing_rhythm
Local stdio connector: node src/mcp-stdio.ts --tool=paperwell-writing-rhythm

{
  "mcpServers": {
    "paperwell-writing-rhythm": { "type": "http", "url": "https://paperwellwritingrhythm.usefulweb.app/mcp" }
  }
}