list_pagesInspect open browser tabs without navigating, returning URLs and titles so you can identify active authenticated pages.
Inspect open browser tabs without navigating. Returns URLs and titles; it does not capture page content.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| count | Yes | ||
| pages | Yes |
Changes observed during successful MCP inspections.
v4.0.0Output schema / (root)Previous value: -nullNew value: +{
+ "$schema": "http://json-schema.org/draft-07/schema#",
+ "additionalProperties": false,
+ "properties": {
+ "count": {
+ "type": "number"
+ },
+ "pages": {
+ "items": {
+ "additionalProperties": false,
+ "properties": {
+ "title": {
+ "type": "string"
+ },
+ "url": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "url",
+ "title"
+ ],
+ "type": "object"
+ },
+ "type": "array"
+ }
+ },
+ "required": [
+ "pages",
+ "count"
+ ],
+ "type": "object"
+}v2.0.7Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: it does not navigate (no side effects on the pages) and 'does not capture page content', explicitly bounding what the tool will and will not return. That boundary is the kind of detail annotations cannot express.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two short sentences, zero filler, with the scope constraint ('without navigating') placed first and the output/limitation statement second. Every clause earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a zero-parameter, read-only, idempotent list tool with an output schema present, the description covers everything needed to call it correctly: what it enumerates, that it has no navigation side effect, and what data it returns versus omits. Return-value detail is legitimately delegated to the output schema.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool takes zero parameters, which is the baseline-4 case per the rubric. There is nothing for the description to clarify, and it correctly describes the output shape (URLs and titles) instead of inventing parameters.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb (Inspect) and resource (open browser tabs), and the qualifier 'without navigating' narrows the scope precisely. It does not name or differentiate against siblings like close_browser or auth_fetch, but the resource is unambiguous enough that confusion is unlikely.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Usage is implied by the phrase 'open browser tabs' rather than stated: an agent can infer this is the tool for enumerating existing tabs. There is no explicit when-to-use condition, no exclusions, and no reference to the sibling tools that also touch browser state.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.