API & MCP

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

HTTP API

• GET https://playcards.usefulweb.app/api/v1/tools – catalog
• GET https://playcards.usefulweb.app/api/v1/tools/{id} – inputs, output schema, examples
• POST https://playcards.usefulweb.app/api/v1/tools/{id}/calculate – run a tool
• GET https://playcards.usefulweb.app/api/v1/workflows · POST https://playcards.usefulweb.app/api/v1/workflows/{id}/run
• OpenAPI 3.1: /openapi.json · /openapi.yaml
• Errors: application/problem+json; 422 includes per-field errors.

Tools on Playcards

• Skat Game Value Calculator – Skat game value from contract, matadors, Hand, Schneider, Schwarz and Ouvert — with overbid check. playcards_skat_game_value
• Doppelkopf Score Calculator – Doppelkopf game points from card points, announcements and special points (DDV rules). playcards_doppelkopf_score
• Blackjack Basic Strategy Calculator – Blackjack basic strategy chart and expected values computed for your table rules. playcards_blackjack_strategy

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://playcards.usefulweb.app/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
• Tools: playcards_skat_game_value, playcards_doppelkopf_score, playcards_blackjack_strategy
• Local stdio connector: node src/mcp-stdio.ts

{
  "mcpServers": {
    "usefulweb": { "type": "http", "url": "https://playcards.usefulweb.app/mcp" }
  }
}