Start using Ostler: read, cite and fill on local test pages

Install Ostler, run doctor, connect your MCP client, then try a checked citation or a verified form fill on local test pages without touching real services.

On this page

1. Install
2. Check it works
3. Connect your agent
4. Try the demo
What the agent sees
Research
A form
Things to ask your agent
Optional: memory
Next steps

Install Ostler, check that it can drive Chrome, connect your agent, and try it on a demo page: read and cite a source, or fill a form. About five minutes.

1. Install#

You need Chrome or Chromium (Ostler drives a real browser) and Python 3.8+ (no Rust needed).

pip install ostler-mcp

No Python? Use the install script (macOS and Linux): curl -fsSL https://inamdarmihir.github.io/ostler/install.sh | sh. With Rust 1.89+ you can build from source: cargo install --git https://github.com/inamdarmihir/ostler ostler. Every option, and what is not published yet (npm, crates.io, Homebrew), is on the Install page.

2. Check it works#

ostler doctor

ostler doctor launches Chrome, round-trips a page and, if you configured Qdrant, prints a memory report (sealing, key location, where embeddings are computed, isolation, transport) and checks that Qdrant is reachable. When something is wrong it prints the command that fixes it; ostler doctor --fix applies the safe ones (creating the config directory). With no config at all, memory is in-process for the session and nothing needs Qdrant or a key. See Troubleshooting if it does not pass.

3. Connect your agent#

ostler install --client claude-code      # or claude-desktop | cursor | vscode | windsurf | codex

That writes the entry into the client's config file with the binary's absolute path: it backs the file up first, keeps your other servers, refuses a malformed file and prints what changed (--dry-run previews, --uninstall removes). ostler install --list shows every client. To only print a snippet instead, use ostler setup <client>. Prefer your own Chrome window? See "Use your own Chrome" on the Install page. Details for every client are in Use with your agent.

After installing or rebuilding ostler, reconnect the MCP client (Claude Code: /mcp; others: restart it) so it starts the new binary.

4. Try the demo#

ostler fixtures        # serves synthetic test pages at http://127.0.0.1:8787

Pick one. Nothing real is read or submitted; these are bundled test pages.

Research with a checked quote. Ask your agent:

Read http://127.0.0.1:8787/packs/research/kestrel-lock.html. Who designed the Kestrel Lock and when did it open? Cite every claim with cite and call evidence before answering.

Ostler reads the page, accepts a quote that is on it, refuses one that is not, and lists any page it could not read. The full walk-through, with unedited output, is in Research with checked citations.

Fill a form. Ask your agent:

Open http://127.0.0.1:8787/dependent.html and fill in the shipping form for Ada Lovelace in Germany, Bavaria.

Ostler fills Country, watches State load, reads every value back, and reports what the page said.

What the agent sees#

Research#

Unedited output from the bundled research pages (ostler serve --tools research), captured 2026-11-06. The <page_content untrusted="true"> tags mark text that came from the page.

> cite {"url": "http://127.0.0.1:8787/packs/research/kestrel-lock.html", "quote": "opened in 1887 and was designed by Marta Ilves"}
VERIFIED [1] <page_content untrusted="true">http://127.0.0.1:8787/packs/research/kestrel-lock.html</page_content> (read 2026-11-06T16:01:32Z, sha256:9f602117)
<page_content untrusted="true">opened in 1887 and was designed by Marta Ilves</page_content>
Check it yourself (best effort): http://127.0.0.1:8787/packs/research/kestrel-lock.html#:~:text=opened%20in%201887%20and%20was%20designed%20by%20Marta%20Ilves

> cite {"url": "http://127.0.0.1:8787/packs/research/kestrel-lock.html", "quote": "Tomas Reyes designed the Kestrel Lock in 1887"}
NOT VERIFIED: these words are not on <page_content untrusted="true">The Kestrel Lock</page_content>. Do not state this claim as sourced; quote the page's own words, not a summary.
Closest text on the page (similarity 0.48): <page_content untrusted="true">The Kestrel Lock The Kestrel Lock is a double</page_content>

cite proves the words are on the page, not that the claim is true.

A form#

Real output from the bundled fixtures (ostler serve --tools forms), lightly reformatted. State is disabled until Country is chosen.

> form_inspect
form [e2] fingerprint=07efd5b3061187a1
  e3 text    "Recipient"      [required]
  e4 select  "Country"        [required] options: Choose… | United States | Germany | India
  e5 select  "State / region" [required, disabled] options: (Choose a country first)
  e6 text    "City"
  e7 submit  "Ship it"

> form_fill {"Country": "Germany", "State": "Bavaria", "Email": "ada@example.com"}
Filled 2/2 fields in 386ms (form e2).
  OK e4 "Country" = "de"
  OK e5 "State / region" = "by"        <- options loaded after Country changed
  UNMATCHED key "Email": no field on the page matches this key
Still empty and required:
  e3 "Recipient"

> form_submit
NOT ACCEPTED: the page reported problems.
  e3 "Recipient": "Please fill in this field."

A key that matches nothing is reported, not guessed. A rejected submit says why, in the page's words. More on how this works in Forms and verification.

Things to ask your agent#

"Find out what this page says about the rate limit and quote the sentence. Say so if you could not read it." (read, cite, evidence)
"Compare the pricing on these three pages and tell me what you could not check." (open_many, evidence)
"Open this web app, click through the signup flow and tell me what breaks." (navigate, click, look)
"Fill in the contact form on this page with my details." (after memory_remember of your name and email, or with --learn)
"Sign up for the newsletter on example.com, but ask me before you submit." (--require-confirm-submit)
"This form has a date picker and a country dropdown: fill it and tell me anything you couldn't verify."
"What's blocking this page?" (look shows numbered click targets; a CAPTCHA is reported, not bypassed)

Optional: memory#

Browsing, reading, citing and form filling need no account and no key (only search needs a provider). Memory is separate and optional:

ostler init                                   # saves your Qdrant URL, key and privacy choices (sealing, embeddings, retention); tests the connection
ostler install --client claude-code -- --learn --lean # re-register with memory flags

See Memory and privacy for exactly what is stored and what is hidden.

Next steps#

Use with your agent: Claude Code, Codex, Cursor, VS Code, anything else.
Tools reference: all 32 tools and their parameters.
Security model: the allowlist, uploads, dialogs, CAPTCHAs.

View this page’s source on GitHub