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ZennoBrowser MCP Server

Official

Adds a web extension to the specified preset.

create_extension_from_web

Add a web extension from a URL to a specified browser preset, enabling agents to configure ZennoBrowser profiles with the extensions they need.

Instructions

Adds a web extension to the specified preset.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
urlNoWeb extension URL. For example, the Chrome web store URL of the extension.
presetIdYesTarget preset ID
workspaceIdNoWorkspace ID. Use -1 for the default workspace

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

C2.3/5.0
Behavior2/5

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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the mutation profile is covered by structured data. The description adds nothing on top of that: it does not say whether the URL is fetched server-side, what happens when the same extension is added twice, or whether the preset is mutated in place.

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?

It is a single short sentence with no padding, so it is not bloated. However, because it merely echoes the title, the sentence does not really earn its place as a separate description field.

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 three-parameter mutation tool with no output schema, the description leaves the agent without the return shape, error behavior, or the distinction from create_extension_from_file. Annotations cover safety hints, but the functional context is essentially absent.

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

Parameters3/5

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

Schema description coverage is 100%, and the schema documents url, presetId, and workspaceId (including the -1 default convention) clearly. The description contributes no additional parameter meaning, so the baseline 3 applies when the schema carries the full load.

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

Purpose2/5

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

Tautological: description restates name/title.

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?

There is no when-to-use guidance, no statement of prerequisites (e.g. whether the preset must exist), and no mention of the alternative create_extension_from_file for local packages. The agent must infer the choice between web-based and file-based extension creation entirely on its own.

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