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stop

Bring a locomotive to a controlled stop at speed 0% by specifying its DCC address. Use for normal halts like end of run or waiting at a signal.

Instructions

Bring a locomotive to a controlled stop (speed 0%), like releasing the throttle.

Args: address: The locomotive's DCC address. Acquires the throttle automatically if this session doesn't already hold it.

For a panic/safety stop (derailment risk, collision course, or any "stop it NOW") use emergency_stop instead — JMRI treats it as a distinct decoder command (an immediate power cut to the motor), not just "speed 0". Use this stop tool for a normal, intentional halt (end of a run, waiting at a signal, user just says "stop the 3").

Safe to call repeatedly, including when the loco is already stopped: JMRI silently ignores a redundant "already at this speed" request instead of replying, and this tool's client keeps a local speed cache continuously refreshed by JMRI's own state broadcasts (which fire for ANY client's changes, not just this tool's), so a repeat call still returns the correct current speed_percent (very likely 0) without hanging or erroring.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
addressYes
Behavior5/5

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

No annotations provided, so description fully discloses behavior: acquires throttle automatically, client-side speed cache, state broadcasts, redundant call handling. Also contrasts with emergency_stop's decoder command difference.

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?

Well-structured with clear sections, but slightly longer than minimal. Every sentence adds value, so still effective.

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?

Comprehensive for a stop command given siblings like emergency_stop and set_speed. Covers behavior, parameter, and usage guidance without needing output schema.

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

Parameters5/5

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

Input schema has 0% coverage, but description adds meaning: explains address as DCC address and notes automatic throttle acquisition, which is not in 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?

Clearly states 'Bring a locomotive to a controlled stop (speed 0%)' and distinguishes from emergency_stop by specifying normal vs panic stop. Uses specific verb-resource combination and contrasts with sibling tool.

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

Usage Guidelines5/5

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

Explicitly says when to use this tool (normal halt) vs emergency_stop (panic stop) and mentions it's safe to call repeatedly, including when already stopped.

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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