webmint

Turn a website into a deterministic, verified tool — using whatever model your agent already runs.

No OpenAI key. No cloud. No sandbox. The artifact is a JSON file you own.

hermes plugins install DECRUX9812/webmint

That's it. The first mint provisions its own browser if needed; webmint_setup does it explicitly if you'd rather pre-install.

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Why

Every agent demo ends the same way: it opens a browser, reads the screen, and guesses. Tomorrow the page moves and the agent guesses differently.

webmint learns the page once, turns it into a declarative spec, proves the spec twice, and then runs it as plain data — no model in the loop, ~3.5 s per call, same fields every time.

browser agent:  open browser → load → read pixels → parse → hope      (~31 s, shape varies)
webmint tool:   run_website_tool(query="...") → [{title, price}]      (~3.5 s, typed)

What makes it different

Model-agnostic	The mint calls the host's own ctx.llm. Whatever provider/model your agent is on does the work — DeepSeek, Gemini, a local model. Nothing is hardcoded to one vendor.
Verified, not vibes	A tool is saved only if it runs twice, returns rows both times, and every declared field is non-empty in most rows. A spec that returns 25 rows of null is rejected and repaired, not shipped.
You own the artifact	tool.json — readable, editable by hand, committable. No service holds your integrations.
Signed-out by design	Every capture uses a fresh browser with no cookies or saved logins, and minted specs never replay Cookie/Authorization. Capture actions can fill, click and press keys on the page, and an http spec replays the captured request (GET or POST). Only public http(s) URLs are opened; loopback/private hosts need WEBMINT_ALLOW_PRIVATE_URLS=1.

Tools

tool	what it does
webmint_setup	Check/provision Node, Playwright and Chromium (about 120 MB once). Idempotent.
webmint_mint	Capture a URL → the model writes a spec → run twice → save only if both runs agree
webmint_run	Execute a minted spec with new inputs (no model)
webmint_list	List minted tools with site, kind and verified state
webmint_remove	Delete a tool and its capture

Ask your agent:

Mint a tool for https://news.ycombinator.com/from?site=github.com that lists posts with title and url.

Then:

Use it for rust-lang.org.

Requirements

• Node >= 18 — found automatically ($WEBMINT_NODE, ~/.local/node24/bin/node, PATH, /usr/local/bin, /usr/bin; version checked).
• Playwright + Chromium — found in $WEBMINT_PW_MODULES, the plugin's own node_modules, an existing Pomerado install, or the global npm root. If none is present, webmint_mint provisions it automatically (set WEBMINT_NO_AUTO_SETUP=1 to opt out).
• URL policy — the mint URL, goto actions, minted url_templates and every redirect must be public http(s). Inside Hermes the host's URL safety check decides (honours security.allow_private_urls); standalone, set WEBMINT_ALLOW_PRIVATE_URLS=1 to reach loopback/private hosts. Link-local and cloud-metadata addresses are always refused.
• Everything else is stdlib Python.

Artifact

$HERMES_HOME/webmint/tools/<name>/
├── tool.json     the spec (hand-editable; hand-written specs are first-class)
├── meta.json     provenance: model, runs, fill rates, timing, example input
└── capture/      the recording it was built from

A spec:

{
  "name": "letterboxd_films",
  "kind": "dom",
  "url_template": "https://letterboxd.com/search/films/{query}/",
  "item_selector": "ul.results > li.search-result",
  "fields": {"title": "a.film-title", "year": "small.metadata a", "url": "a@href"},
  "input_schema": {"properties": {"query": {"type": "string"}}, "required": ["query"]},
  "limit": 20
}

Field expressions: "css", "css@attr", "+ .x" (next sibling), "^ .x" (parent) — the last two exist because real pages split one record across sibling elements (arXiv's <dt>/<dd>).

kind: "http" replays a captured JSON endpoint instead (method, headers, body_template, items_path, field_paths).

Measured

Six tools, eight sites, minted with deepseek-v4.1-flash (2026-10-26):

tool	mint	run	rows	field fill
wikipedia_search	28.3 s	3.1 s	20	100%
arxiv_recent	64.2 s (1 repair)	2.7 s	25	100%
github_trending	29.5 s	4.0 s	14	93% lang
books_scrape	15.4 s	2.7 s	19	100%
hn_github_posts	18.8 s	2.5 s	30	100%
letterboxd_films	32.4 s	4.9 s	20	100%

mean mint 31.4 s · mean run 3.5 s · 6 of 8 sites mintable · break-even ≈ 10 runs

Honest limits

• Bot walls. Headless Chromium gets 403 on some sites (Chewy, eBay) and an empty page on others (DuckDuckGo). Two of eight test sites failed this way. No prompt fixes a fingerprint — that needs your own browser profile, which is not in v0.1.
• Not strictly read-only. It never logs in or uses your cookies, but capture actions can fill and submit page forms, and an http spec replays the captured request, POST included.
• Selectors rot. meta.json records when a tool was verified; re-mint when a run starts returning zero rows. A repair cron is not included.
• Weak models produce worse specs. The verifier turns that into a visible failure rather than a silent one, which is the most that can be promised.

Tests

python3 -m pytest tests/ -q     # 13 tests: validation, store, verifier gates, real browser fixtures

Two tests launch Chromium against a local HTML fixture — the extractor and the sibling prefix are covered without touching the network.

Credits

Pomerado — github.com/Pomerado/pomerado, MIT — made the case that a website should be learned once and replayed instead of re-reasoned every run. webmint is an independent implementation of that idea for Hermes Agent: the same shape (capture → spec → verify → tool), rebuilt so the learning step runs on whatever model you already have, with the artifact as a JSON spec you own rather than generated source. Their Guardian/authority model and job contract are worth reading; nothing is copied here.

The conversation this came from — @Gamma_950 ("your browser agent re-reasons every page on every run"), @sreecharantwts ("browser use being slow and flaky is the real tax on agents"), @stretchcloud (structure loss in markdown flattening), @pamelafox (WebMCP as the endgame). Those posts are the reason the pitch is about verification, not speed.

License

MIT © Ritesh Patel