Tape any API to your agent in one command. DuckTap is a CLI factory for AI agents. Point it at an OpenAPI spec, a HAR file, or a plain website, and it prints a Python CLI, an MCP server, and a Claude/Cursor/Codex skill — wired up, cached, scored, ready to ship.
Website: ducktap-website.vercel.app
DuckTap is inspired by Printing Press by @mvanhorn — same north star (muscle memory for agents) — rebuilt in Python with multi-LLM support, a web dashboard, Playwright-powered browser sniffing, and a real plugin system.
$ ducktap press tests/fixtures/petstore.yaml --out ./out --name petstore
Pressed petstore (19 operations) -> out
python-cli: 10 files
mcp-server: 5 files
skill: 3 files
Scorecard: 92/100 (A)
- coverage: 95 — 19 operations exposed
- documentation: 100 — 19/19 operations have docs
- auth: 100 — 2 auth scheme(s)
- typed_params: 54 — 29/53 params typed/enum
- artifacts: 100 — 3/3 expected artifact dirs present
- naming: 100 — 19/19 unique operation ids
In a world of AI agents, a well-designed CLI is muscle memory. No hunting through docs, no wrong turns, no wasted tokens. DuckTap reads the spec, sniffs the traffic when no spec exists, and prints:
- A Python CLI (
<api>-dt-cli) — Click-based, auth from env vars, JSON by default, pretty mode for humans, local SQLite mirror for compound queries, retries on transient errors. - An MCP server (
<api>-dt-mcp) — every operation exposed as an MCP tool, stdio transport, drop into Claude Desktop or Cursor in 60 seconds. - A skill for Claude Code, Cursor (
.mdc), and a generictools.json— so any agent harness can pick up where the others left off. - A scorecard grading coverage, docs, auth clarity, typed params, artifacts, and naming.
pip install ducktap
ducktap --versionFor browser sniffing (optional):
pip install "ducktap[sniff]"
playwright install chromiumRequires Python 3.11+.
Developer install (contributing to DuckTap itself)
git clone https://github.com/zanni098/DuckTap
cd DuckTap
pip install -e ".[dev]"
python -m pytest tests/ -q # 44 passed# 1. Press a built-in catalog entry (no URL needed)
ducktap catalog list # browse 17 built-in APIs
ducktap catalog print stripe # press Stripe CLI + MCP + skill
# 2. From any OpenAPI spec URL
ducktap press https://petstore3.swagger.io/api/v3/openapi.yaml
# 3. From a local spec or HAR file
ducktap press ./openapi.yaml --name myapi
ducktap press ./traffic.har --name myapi
# 4. From a website with no public spec (needs [sniff] extra)
ducktap sniff https://example.com
# 5. Open the dashboard
ducktap ui # http://127.0.0.1:8765Running ducktap press prints something like:
Pressed petstore (19 operations) -> ./out
python-cli: 10 files
mcp-server: 5 files
skill: 3 files
Scorecard: 92/100 (A)
- coverage: 95 — 19 operations exposed
- documentation: 100 — 19/19 operations have docs
- auth: 100 — 2 auth scheme(s)
- typed_params: 54 — 29/53 params typed/enum
- artifacts: 100 — 3/3 expected artifact dirs present
- naming: 100 — 19/19 unique operation ids
What you get under ./out/:
out/
├── petstore-dt-cli/ # pip install -e . → petstore-dt-cli --help
│ ├── pyproject.toml
│ ├── README.md
│ ├── petstore_dt_cli/
│ │ ├── main.py
│ │ ├── commands.py # one click subcommand per API operation
│ │ ├── client.py # httpx + env-var auth + retries
│ │ └── mirror.py # local SQLite cache
│ └── tests/test_smoke.py
├── petstore-dt-mcp/ # pip install -e . → add to Claude Desktop config
│ └── petstore_dt_mcp/server.py
└── skills/ducktap-petstore/
├── SKILL.md # Claude Code skill
├── ducktap-petstore.mdc # Cursor rule
└── tools.json # generic agent tool definitions
| Printing Press | DuckTap | |
|---|---|---|
| Language | Go | Python — easier to extend, richer LLM ecosystem |
| LLM | Claude only | Multi-LLM via LiteLLM (Anthropic, OpenAI, Gemini, Ollama, Groq, Azure) |
| Skills | Claude Code | Claude Code + Cursor .mdc + generic tools.json |
| UI | None | Local FastAPI dashboard (ducktap ui) |
| Plugins | Source fork | Entry-point plugin system — drop-in discoverers & generators |
| Browser sniff | Custom Go browser | Playwright — full HAR export, scriptable actions |
| Generated CLI runtime | Single Go binary | Python (pip-installable, hackable, single-file editable) |
See docs/COMPARISON.md for the full feature matrix.
ducktap press <source> # discover + generate (the default loop)
ducktap research <source> # discover only — emit normalized APISpec JSON
ducktap sniff <url> # browser-sniff a site (needs [sniff] extra)
ducktap scorecard <source> # quality scorecard
ducktap shipcheck <name> # structural & runtime sanity checks
ducktap catalog list|print # browse the recipe library
ducktap plugins list # show installed discoverers + generators
ducktap ui # local web dashboard
Add a discoverer or generator without forking. Register via Python entry points:
# your_plugin/pyproject.toml
[project.entry-points."ducktap.plugins"]
mything = "your_plugin.module" # module just calls plugins.register_discoverer(...)See docs/PLUGINS.md and the sample at
src/ducktap/plugins/builtin/graphql_intro.py.
input (URL | spec | HAR)
│
▼
┌─────────────┐
│ Discovery │ openapi / har / browser-sniff / graphql (plugin) / …
└──────┬──────┘
▼
APISpec (Pydantic) ──── intermediate normalized representation
│
▼
┌─────────────┐
│ Generator │ python-cli / mcp-server / skill / …
└──────┬──────┘
▼
artifacts/ (CLI pkg + MCP pkg + SKILL.md + cursor.mdc + tools.json)
│
▼
┌─────────────┐
│ Verify │ scorecard + shipcheck + (optional) live smoke test
└─────────────┘
See docs/ARCHITECTURE.md.
See docs/ROADMAP.md. Highlights for v0.2+:
- LLM-assisted polish step (operation descriptions, command names, doc strings)
- GraphQL first-class (today: plugin, beta)
- Auth doctor — detect login flows during sniffing, emit accurate auth blocks
- Compound query macros (canonical "what's interesting about X" recipes)
- CLI publish to PyPI + GitHub in one command
MIT — see LICENSE.
Inspired by Printing Press by Matt Van Horn and the agent-CLI playbook proved out by discrawl and gogcli.