browser_fill
Fill controlled form inputs in React, Vue, or Svelte apps via CDP. Targets by CSS selector or semantic axis (text, regex, role, ariaLabel). Resolves to a single element; stops with clear errors on ambiguity or non-fillable targets.
Instructions
Fill a form input with a value via CDP — works on React/Vue/Svelte controlled inputs that reject browser_eval value assignment. Two ways to target: (1) selector — a CSS selector (use browser_overview / browser_locate to find one); or (2) by-axis (semantic) — by:'text'|'regex'|'role'|'ariaLabel' + pattern (e.g. by:'ariaLabel', pattern:'Email address', or by:'role', pattern:'textbox'), so you do not have to build a CSS selector. by-axis resolves to a SINGLE fillable element and STOPS with code:'BrowserAmbiguousTarget' (candidates[] + next[] hints) when 2+ match, or code:'BrowserNoActionableTarget' when the match is not a fillable input/textarea/contenteditable — it never guesses. Optionally add role to filter and scope to narrow. Provide EITHER selector OR by+pattern (not both). Use this over browser_eval when setting a controlled input's value via JS does not update framework state. Caveats: Requires browser_open (CDP active). actual in the response shows the element's value after fill; verify it matches the intended value. Typed errors: code:'BrowserFillNotDelivered' on post-fill value mismatch — note the false-positive case where a React controlled input's onChange transforms the value (delivery actually succeeded; hints.verifyDelivery.subReason:'controlled_input_transform' for that case; the actual value is authoritative).
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| by | No | Semantic axis to target by INSTEAD of a CSS selector: 'text' (visible text), 'regex', 'role' (ARIA/implicit role), 'ariaLabel'. Pair with pattern. Resolves to a SINGLE actionable element and STOPS with candidates when ambiguous. | |
| port | No | Chrome/Edge CDP remote debugging port. | |
| role | No | Optional ARIA/implicit-role filter AND-combined with by (e.g. by:'text', pattern:'Save', role:'button'). | |
| scope | No | Optional CSS selector to limit the by-axis search scope (disambiguation). | |
| tabId | No | Tab ID from browser_open. Omit to use the first page tab. | |
| value | Yes | Text to fill into the input element | |
| include | No | Optional response-shape opt-in. `['envelope']` returns the self-documenting envelope (`_version` / `data` / `as_of` / `confidence`). `['raw']` forces raw shape (overrides DESKTOP_TOUCH_ENVELOPE=1 server default). Default behaviour is raw shape (compat with existing clients). | |
| pattern | No | Value matched against the chosen by axis (required when by is set). | |
| selector | No | CSS selector for the input element. Provide EITHER selector OR by+pattern. | |
| caseSensitive | No | Case-sensitive matching for by:'text'/'regex' (default false). | |
| includeContext | No | When true, append activeTab and readyState context to the response. |