BrowserAttach

Overview Schema Source Related Servers Discussions Admin

browser_scroll

Scroll a page, container, or viewport by pixel offsets, or search until specified text appears in visible DOM content. Returns a fresh ref and reports stop reason and confirmed progress.

Instructions

Scroll one ref/selector container or viewport x/y (default center). DOM emits no wheel events; wheel sends native wheel input. until returns a fresh ref. Stopped searches report stop_reason, scroll_pending and confirmed progress; a boundary/miss does not prove end of data.

Input Schema

Name	Required	Description	Default
`x`	No
`y`	No
`nth`	No	Selector only: zero-based DOM index, AX tree order for role.
`ref`	No
`mode`	No		dom
`name`	No	role only: exact AX name; empty allowed.
`frame`	No	Child frame: at least one of url/title/path. url/title exact; path=unique nested CSS iframe steps (e.g. ["#frame"]); exclusive with frame_id.
`until`	No	DOM-only search of visible elements' textContent; selector is a CSS filter within the container.
`delta_x`	No
`delta_y`	No	Vertical delta, positive down; required without until.
`observe`	No	Read this explicit control after the action within its remaining budget; observation is separate from delivery. No assertion or automatic replay.
`frame_id`	No	Selector frame; default main.
`selector`	No	Query by selector_type; role example: selector="link", name="Claim".
`max_steps`	No
`tab_handle`	Yes
`timeout_ms`	No	Total preparation/dispatch/verification and optional observation budget.
`dialog_policy`	No	accept/dismiss auto-handle dialogs and return their messages.	ask
`selector_type`	No	Default css. label: exact associated HTML label, whitespace normalized. placeholder: exact attribute.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv0.28.2Oct 29, 2026

addedInput schema / properties / observe

Added value: +{
+  "additionalProperties": false,
+  "description": "Read this explicit control after the action within its remaining budget; observation is separate from delivery. No assertion or automatic replay.",
+  "properties": {
+    "frame": {
+      "additionalProperties": false,
+      "description": "Child frame: at least one of url/title/path. url/title exact; path=unique nested CSS iframe steps (e.g. [\"#frame\"]); exclusive with frame_id.",
+      "properties": {
+        "path": {
+          "items": {
+            "minLength": 1,
+            "type": "string"
+          },
+          "maxItems": 16,
+          "minItems": 1,
+          "type": "array"
+        },
+        "title": {
+          "minLength": 1,
+          "type": "string"
+        },
+        "url": {
+          "minLength": 1,
+          "type": "string"
+        }
+      },
+      "type": "object"
+    },
+    "frame_id": {
+      "description": "Selector frame; default main.",
+      "type": "string"
+    },
+    "max_chars": {
+      "default": 16000,
+      "maximum": 64000,
+      "minimum": 1000,
+      "type": "integer"
+    },
+    "max_options": {
+      "default": 30,
+      "maximum": 100,
+      "minimum": 1,
+      "type": "integer"
+    },
+    "name": {
+      "description": "role only: exact AX name; empty allowed.",
+      "maxLength": 10000,
+      "type": "string"
+    },
+    "nth": {
+      "description": "Selector only: zero-based DOM index, AX tree order for role.",
+      "maximum": 9007199254740991,
+      "minimum": 0,
+      "type": "integer"
+    },
+    "popup_selector": {
+      "description": "Optional unique CSS popup in the control frame; otherwise use browser-resolved controls/owns relations and control descendants.",
+      "maxLength": 10000,
+      "minLength": 1,
+      "type": "string"
+    },
+    "ref": {
+      "type": "string"
+    },
+    "selector": {
+      "description": "Query by selector_type; role example: selector=\"link\", name=\"Claim\".",
+      "maxLength": 10000,
+      "minLength": 1,
+      "type": "string"
+    },
+    "selector_type": {
+      "description": "Default css. label: exact associated HTML label, whitespace normalized. placeholder: exact attribute.",
+      "enum": [
+        "css",
+        "xpath",
+        "label",
+        "placeholder",
+        "role"
+      ],
+      "type": "string"
+    },
+    "timeout_ms": {
+      "default": 1000,
+      "maximum": 5000,
+      "minimum": 100,
+      "type": "integer"
+    }
+  },
+  "type": "object"
+}

changedInput schema / properties / timeout_ms / description

Previous value: -"Total preparation/dispatch/verification budget."New value: +"Total preparation/dispatch/verification and optional observation budget."

Changed10 schema fields changedv0.24.2Oct 27, 2026

changedInput schema / properties / delta_y / description

Previous value: -"Positive scrolls down."New value: +"Vertical delta, positive down; required without until."

changedInput schema / properties / dialog_policy / description

Previous value: -"accept/dismiss returns handled dialog messages."New value: +"accept/dismiss auto-handle dialogs and return their messages."

changedInput schema / properties / frame / description

Previous value: -"Exact child-frame URL/title or CSS iframe path (e.g. [\"#content_iframe\"]); alternative to frame_id. Each path entry uniquely selects an iframe in the preceding document."New value: +"Child frame: at least one of url/title/path. url/title exact; path=unique nested CSS iframe steps (e.g. [\"#frame\"]); exclusive with frame_id."

changedInput schema / properties / frame_id / description

Previous value: -"Selector scope; defaults to main frame."New value: +"Selector frame; default main."

changedInput schema / properties / name / description

Previous value: -"role only: exact accessible name; may be empty."New value: +"role only: exact AX name; empty allowed."

changedInput schema / properties / nth / description

Previous value: -"Zero-based match index: DOM order, or AX tree order for role."New value: +"Selector only: zero-based DOM index, AX tree order for role."

changedInput schema / properties / selector / description

Previous value: -"CSS/XPath query, HTML label text, exact placeholder or AX role (e.g. selector=\"link\", name=\"Claim\"), according to selector_type."New value: +"Query by selector_type; role example: selector=\"link\", name=\"Claim\"."

changedInput schema / properties / selector_type / description

Previous value: -"Default css. label matches associated HTML labels with whitespace normalized; role uses browser AX semantics."New value: +"Default css. label: exact associated HTML label, whitespace normalized. placeholder: exact attribute."

changedInput schema / properties / timeout_ms / description

Previous value: -"Covers preparation, dispatch and verification."New value: +"Total preparation/dispatch/verification budget."

addedInput schema / properties / until / description

Added value: +"DOM-only search of visible elements' textContent; selector is a CSS filter within the container."

Changed1 schema field changedv0.24.1Oct 26, 2026

changedInput schema / properties / selector / description

Previous value: -"CSS/XPath query, HTML label text, exact placeholder or AX role, according to selector_type."New value: +"CSS/XPath query, HTML label text, exact placeholder or AX role (e.g. selector=\"link\", name=\"Claim\"), according to selector_type."

First observedv0.24.0Oct 26, 2026

TDQS

A3.7/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the behavioral burden and discloses several non-obvious traits: DOM mode emits no wheel events, wheel mode sends native wheel input, stopped searches report stop_reason/scroll_pending/progress, and a boundary/miss does not prove end of data. It does not cover permission requirements or side effects such as lazy-loading triggered by scrolling, so it is strong but not exhaustive.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loaded with the core operation, then adds mode and search behavior without filler. Every sentence provides actionable information, even though the semicolon-heavy style is dense.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For an 18-parameter tool with nested objects, no annotations, and no output schema, the description covers the central scroll action, mode distinction, until/search behavior, and partial return reporting. It omits important context for parameters like observe, frame, selector_type, dialog_policy, max_steps, and timeout_ms, so it is adequate but incomplete for the tool's complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 61%, so the schema already documents a substantial portion of the 18 parameters. The description adds meaning for core behavior: x/y default to center, mode affects whether events are emitted, and until returns a fresh ref. It does not explain many other parameters such as observe, frame, selector_type, max_steps, timeout_ms, or delta handling, leaving a significant parameter-semantics gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and target: 'Scroll one ref/selector container or viewport x/y (default center).' It also distinguishes DOM versus wheel scrolling behavior. It does not explicitly differentiate this tool from sibling alternatives such as browser_press_key or browser_wait, so it falls short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives useful implied guidance by explaining the two mode behaviors ('DOM emits no wheel events; wheel sends native wheel input') and that 'until returns a fresh ref.' However, it does not explicitly say when to use browser_scroll rather than browser_press_key, browser_wait, or other siblings, nor does it state exclusions or prerequisites.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

browser_scroll

Instructions

Input Schema

Schema Changelog

TDQS

Other Tools