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zen-browser

zen-browser

by grapedjuice
OverviewSchemaSourceRelated ServersDiscussionsAdmin
JavaScript
Local

tabs_select

Switch to a specific browser tab by ID, bringing it into focus so you can continue interacting with that page.

Instructions

Switch to (activate) a tab.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "tabId": "<tabId>"
    },
    "name": "tabs_select"
  }
}

Input Schema

NameRequiredDescriptionDefault
tabIdYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.0.0

TDQS

C2.7/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full behavioral burden, yet it only restates the operation. It doesn't say whether activation changes focus, whether it fails for unknown/closed tab IDs, or what side effects occur on page state.

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?

A single short sentence with the core action front-loaded and no filler. Its brevity is appropriate in form, though it tips into under-specification rather than verbosity.

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

Completeness2/5

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

For a one-parameter state-mutating tool with no annotations or output schema, the description should at minimum explain tabId's provenance and what activation implies. Those gaps leave an agent guessing about inputs and effects.

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

Parameters2/5

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

The single parameter has 0% schema description coverage, so the schema gives only 'integer' with wide numeric bounds and no meaning. The description adds nothing about tabId — not its origin, validity, or whether -1 or special values are meaningful.

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?

States a specific verb (switch to/activate) and resource (a tab), making the effect on browser state unambiguous. It doesn't explicitly contrast with siblings like tabs_create or tabs_close, but the intent is distinct enough for an agent to select it over those.

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

Usage Guidelines2/5

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

No guidance on when to use this versus tabs_context or navigate, and no mention of where a valid tabId comes from (presumably tabs_context). The agent must infer that a tab must already exist; nothing states prerequisites or failure conditions.

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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