PNETLab MCP Server

list_running_labs

Retrieve all active lab sessions on the PNETLab server, including session IDs and pod status, to identify labs blocking deletion of their .unl files.

Instructions

List every currently-running lab session on the server (across all users): lab path, session id, pod, and running-node count. A lab shows here whenever it has an open pod — that's what blocks deleting its .unl ('error_lab_running').

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": "list_running_labs"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 10, 2026

TDQS

A4.1/5.0

Behavior4/5

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

With no annotations, the description carries the full burden. It explains the condition for a lab being listed ('has an open pod') and the behavioral implication (blocks deleting .unl files). No destructive behavior or rate limits are mentioned, but it is sufficient for a read-only list tool.

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 two sentences, front-loaded with the primary purpose and return fields. Every sentence adds value with no waste.

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?

The output schema exists, so the description does not need to explain return values. It covers the tool's purpose, the condition for a lab being listed, and a practical use case (blocking deletions). Complete for a zero-parameter list tool.

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?

The input schema has zero parameters, so schema description coverage is 100%. The description adds no parameter details, but none are needed. Baseline 3 applies as it does not add 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 states the verb 'list' and the resource 'current running lab sessions', and specifies the returned fields (lab path, session id, pod, running-node count). It distinguishes from sibling tools like 'list_labs' by focusing only on running sessions.

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

Usage Guidelines3/5

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

The description implies usage for checking running labs that block deletions (mentioned via 'error_lab_running'), but does not explicitly state when to use this tool versus alternatives like 'list_labs' or provide exclusion criteria.

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