MrJ-JMRI-MCP

release_all_locomotives

Release throttles on all acquired locomotives without changing speed or direction. Turns off active functions first to prevent direction flips. Use for ending a session or handing off control mid-run.

Instructions

Release this session's throttle on EVERY currently-acquired locomotive, without changing their state.

Call for "release all locomotives"/"libère toutes les locos" — ending a session or handing off without stopping anything. Speed and direction stay untouched; only the throttle is released. Exception: any still-active function (e.g. lights) is turned off first automatically — releasing with one on can flip direction.

NOT park_all_locomotives (also stops, faces forward, lights off before releasing) and NOT emergency_stop_all (stops motion but keeps throttles acquired). Use only to let go of control without changing current locomotive state — e.g. handing off mid-run.

Only reaches locomotives THIS session acquired. Nothing acquired yet returns {"released": []}, not an error.

Returns {"released": [{"address", "released": bool}...]} — one entry per locomotive, attempted independently so one failure doesn't block the rest.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "release_all_locomotives"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.1.0Jul 29, 2026

TDQS

A4.9/5.0

Behavior5/5

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

With no annotations, the description fully discloses behavior: speed/direction untouched, functions turned off if active, only reaches this session's acquired locos, independent attempts per loco, returns empty array for nothing acquired. All important traits are covered.

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?

The description is well-structured: lead sentence, purpose, behavior details, comparisons, edge case, return format. Every sentence adds value without redundancy. Compact yet comprehensive.

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?

Even without an output schema, the description explains the return structure and error handling ('not an error'). It covers all necessary context for a zero-parameter tool, including edge cases and independent execution.

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?

The input schema has zero parameters, so the baseline is 4. The description adds no parameter-level detail (none needed) but explains the tool's effect clearly, which is sufficient for a parameterless tool.

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 starts with a specific verb+resource: 'Release this session's throttle on EVERY currently-acquired locomotive, without changing their state.' It clearly distinguishes from siblings like park_all_locomotives and emergency_stop_all by naming them and contrasting behavior.

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?

The description explicitly states when to use: 'ending a session or handing off without stopping anything.' It also gives exceptions (functions turned off) and contrasts with similar tools, providing clear guidance on alternatives.

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