BrowserAttach

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browser_type

Types printable characters into a focused or selected browser field without clearing existing content, stopping if focus is lost. Use press_key for Enter/Tab and fill for multiline replacement.

Instructions

Type printable characters with trusted keys without clearing. Choose exactly one ref/selector/focused=true; stop on focus loss/detachment. Enter/Tab use press_key; ordinary multiline replacement uses fill.

Input Schema

Name	Required	Description	Default
`nth`	No	Selector only: zero-based DOM index, AX tree order for role.
`ref`	No
`name`	No	role only: exact AX name; empty allowed.
`text`	Yes
`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.
`focused`	No	Pin current editable focus without refocusing; exclusive with ref/selector and locator options.
`observe`	No	Read this explicit control after the action within its remaining budget; observation is separate from delivery. No assertion or automatic replay.
`delay_ms`	No	Between characters: ms or independent uniform [min,max]; min<=max.
`frame_id`	No	Selector frame; default main.
`selector`	No	Query by selector_type; role example: selector="link", name="Claim".
`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 / delay_ms / description

Previous value: -"Between characters: fixed ms or independently sampled uniform [min, max]."New value: +"Between characters: ms or independent uniform [min,max]; min<=max."

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 / focused / description

Previous value: -"Alternative to ref/selector: pin the currently focused editable element without refocusing it. Stops if focus changes."New value: +"Pin current editable focus without refocusing; exclusive with ref/selector and locator options."

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."

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

A4.4/5.0

Behavior4/5

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

With no annotations, the description carries the full burden and does disclose non-obvious traits: it appends rather than replacing text, uses trusted key events (not synthetic value assignment), and stops on focus loss or detachment — i.e. partial input is possible. It stops short of saying what constitutes success/failure or how much text landed when aborted, which matters for a mutation tool.

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

Conciseness4/5

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

Three front-loaded sentences with essentially zero waste: scope, target selection, then sibling routing. It is compressed to the edge of cryptic ("focused=true" as a clause fragment) and would benefit from one clause on outcome, but every sentence earns its place.

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 a 14-parameter tool with nested objects, no annotations, and no output schema, the description covers only targeting and sibling selection. It says nothing about the return value, how timeout_ms/delay_ms affect the write, or how dialog_policy interacts with typing — an agent must infer all of that from the schema alone.

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

Parameters4/5

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

Schema coverage is 79%, so the baseline is 3; the description adds a genuine constraint the schema does not encode — the exclusive-one-of rule across ref/selector/focused. It adds nothing for frame, delay_ms, observe, or dialog_policy, but those already carry schema descriptions.

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

Purpose5/5

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

States a specific verb (type) plus the precise semantics: printable characters, trusted key events, no clearing of existing content. It explicitly distinguishes itself from two siblings, press_key and fill, by naming the exact cases those handle. An agent can identify this tool without opening the schema.

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

Usage Guidelines5/5

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

Names both competing alternatives with selecting conditions (Enter/Tab -> press_key; ordinary multiline replacement -> fill) and states the mutual-exclusion rule for the target options (exactly one of ref/selector/focused=true). Nothing about tool choice or target specification is left to inference.

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

browser_type

Instructions

Input Schema

Schema Changelog

TDQS

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