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pironjulien

nexus-browser

by pironjulien
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JavaScript
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browser_list_tabs

Read-onlyIdempotent

List open Chrome tabs with IDs, titles, URLs, owner agent, and session state so agents can identify owned tabs, recover orphaned tabs, and target the correct page.

Instructions

Lists the tabs open in Chrome (id, title, URL) and, for each, the agent driving it (owner), whether it belongs to THIS session (mine) and its state: "mine" (this session), "orphan" (orphaned by my agent: dead session, take it back with browser_adopt_tab, or close / release it), "other" (another agent or another live session) or "user" (the user's tab, no agent). Full title and URL only for mine=true tabs (opened or adopted by this session); the others show their domain only (url = origin, title null, redacted=true): designate one by its id and domain. Only mine=true tabs accept page commands.

Input Schema

NameRequiredDescriptionDefault

No arguments

Output Schema

NameRequiredDescriptionDefault
dataYes
statusYes
warningNoEmergency stop hotkey not held, or similar notice
untrusted_noteNoPage text that looks like instructions aimed at an AI

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed10 schema fields changedv2.31.6
    • addedOutput schema / $defs
      Added value: +{
+  "Tab": {
+    "additionalProperties": true,
+    "description": "Tab. Full title and URL only for this session's tabs (mine); otherwise title null, url reduced to the origin,\nredacted true. state: mine, orphan, other or user.",
+    "properties": {
+      "active": {
+        "type": "boolean"
+      },
+      "adopted": {
+        "type": "boolean"
+      },
+      "favIconUrl": {
+        "type": "string"
+      },
+      "groupId": {
+        "type": "integer"
+      },
+      "id": {
+        "type": "integer"
+      },
+      "index": {
+        "type": "integer"
+      },
+      "mine": {
+        "type": "boolean"
+      },
+      "owner": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ]
+      },
+      "pinned": {
+        "type": "boolean"
+      },
+      "redacted": {
+        "type": "boolean"
+      },
+      "state": {
+        "type": "string"
+      },
+      "title": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ]
+      },
+      "url": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ]
+      },
+      "windowId": {
+        "type": "integer"
+      }
+    },
+    "title": "Tab",
+    "type": "object"
+  }
+}
    • addedOutput schema / additionalProperties
      Added value: +true
    • addedOutput schema / description
      Added value: +"Tabs open in Chrome."
    • addedOutput schema / properties / data
      Added value: +{
+  "items": {
+    "$ref": "#/$defs/Tab"
+  },
+  "type": "array"
+}
    • removedOutput schema / properties / result
      Removed value: -{
-  "title": "Result",
-  "type": "string"
-}
    • addedOutput schema / properties / status
      Added value: +{
+  "const": "success",
+  "type": "string"
+}
    • addedOutput schema / properties / untrusted_note
      Added value: +{
+  "description": "Page text that looks like instructions aimed at an AI",
+  "type": "string"
+}
    • addedOutput schema / properties / warning
      Added value: +{
+  "description": "Emergency stop hotkey not held, or similar notice",
+  "type": "string"
+}
    • changedOutput schema / required
      Previous value: -[
-  "result"
-]New value: +[
+  "status",
+  "data"
+]
    • changedOutput schema / title
      Previous value: -"browser_list_tabsOutput"New value: +"TabsAnswer"
  2. First observedv0.1.0

TDQS

A4.5/5.0
Behavior5/5

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

Annotations already declare readOnly/idempotent/non-destructive, yet the description adds substantial beyond-schema behavior: redaction rules for non-mine tabs (url = origin, title null, redacted=true), the owner concept, and the four-state model with what each state permits.

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

Conciseness3/5

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

The ownership/state information is front-loaded and earns its place, but it arrives as a dense run-on with an oversized parenthetical enumerating four states, which is harder to parse than a short list. It is informative but not tightly structured.

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

Completeness5/5

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

Even though an output schema exists, the description explains the returned fields and their redaction semantics, which is exactly the context an agent needs to interpret the listing. Nothing needed to call it correctly is missing.

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?

The tool takes zero parameters, so the baseline is 4. The description correctly describes no inputs, and the schema coverage is 100%.

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?

Opens with a specific verb and resource ('Lists the tabs open in Chrome') and enumerates exactly what is returned (id, title, URL, owner, mine, state). The scoping language ('THIS session', 'mine=true tabs') makes it clearly distinct from siblings like browser_active_tab or browser_select_tab.

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

Usage Guidelines4/5

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

Gives actionable routing: orphaned tabs can be reclaimed via browser_adopt_tab or closed/released, and 'Only mine=true tabs accept page commands' tells the agent when other tools will fail. It stops short of an explicit 'call this before X' instruction, but the implied workflow is clear.

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

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