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ZennoBrowser MCP Server

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Stopping Execution Thread.

stop_thread
DestructiveIdempotent

Terminate an active execution thread by its token, closing any associated browser instance if one exists.

Instructions

This method can be used to stop an existing execution thread. Stopping a thread will also stop the associated browser instance, if it exists.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
threadTokenYesThe unique token of the thread to stop (required).
workspaceIdNoWorkspace identifier. -1 means the default workspace.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

A3.6/5.0
Behavior4/5

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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is covered. The description adds genuinely new behavioral context beyond them: stopping a thread cascades to stop its associated browser instance, which is not derivable from the annotations or schema.

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, no filler, and the core action is front-loaded ahead of the side-effect disclosure. Every sentence earns its place.

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

Completeness4/5

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

There is no output schema, and the description covers the key side effect an agent must anticipate (the cascading browser-instance stop). It omits auth/permission requirements and what happens when the thread is already stopped, but the idempotentHint annotation partially covers the latter, so the gap is small.

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%, so threadToken and workspaceId (including the -1 default) are fully documented in the schema. The description adds no extra meaning about parameter format or constraints, so the baseline of 3 is appropriate.

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 and resource ('stop an existing execution thread'), so an agent immediately knows what the tool does. It does not explicitly distinguish itself from the sibling bulk_stop_thread, leaving the singular/plural distinction to be inferred from the name.

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?

The description gives no when-to-use or when-not-to-use guidance, and never names bulk_stop_thread or stop_browser_instance as alternatives for related needs. The only usable context is implicit in the tool name itself, which is insufficient routing guidance for a tool family with several stop-style siblings.

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