gecko-mcp

by Frumane

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TypeScript

Local

navigate_tab

DestructiveIdempotent

Opens a URL in the active browser tab or specifies a tab by ID.

Instructions

Navigate a tab to a new URL. Targets the active tab unless a browserId is given.

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": {
      "url": "<url>"
    },
    "name": "navigate_tab"
  }
}

Input Schema

Name	Required	Description	Default
`url`	Yes	The URL to navigate to.
`browserId`	No	browserId of the tab to navigate (from list_tabs). Defaults to the active tab.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.2.4Jun 20, 2026

TDQS

A4.5/5.0

Behavior4/5

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

The description adds behavioral context beyond annotations by clarifying that it navigates the active tab unless a browserId is provided. Annotations (destructiveHint=true) confirm state changes, and the description aligns with them without contradiction.

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?

Two sentences efficiently convey purpose and key behavioral nuance with no superfluous information. Every word earns its place.

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?

For a simple two-parameter tool with no output schema, the description fully covers what the tool does and how to use it. Annotations supply additional safety context, making the definition complete.

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 100%, providing baseline parameter descriptions. The description reinforces the default behavior for browserId and adds clarity on targeting, adding value beyond the schema.

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?

The description clearly identifies the verb 'Navigate' and the resource 'tab', specifying the action of changing a tab's URL. It distinguishes from sibling tools like 'open_tab' by implying the tab already exists and provides context on targeting the active tab or a specific one via browserId.

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?

The description explicitly states when to use the tool: it targets the active tab by default or a specific tab when browserId is given. While it doesn't explicitly exclude alternatives like 'click' for link navigation, the context is sufficient for basic use.

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