smol-mcp

run-command

Execute shell commands on virtual machines, targeting local or cloud fleets with configurable environment, workdir, and timeout. Returns the guest's exit code.

Instructions

Run a command in a running machine. exitCode comes from the guest; a failing command is not an error.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "name": "<name>",
      "command": "<command>"
    },
    "name": "run-command"
  }
}

Input Schema

Name	Required	Description	Default
`env`	No	Environment variables
`name`	Yes	Machine name
`stdin`	No
`target`	No	Which fleet to talk to. local is smolvm serve on this host; cloud is smol cloud at SMOL_CLOUD_URL.	local
`command`	Yes	argv array, or a string run with sh -c
`workdir`	No
`timeoutSecs`	No

Output Schema

Name	Required	Description	Default
`stderr`	Yes
`stdout`	Yes
`exitCode`	Yes
`timedOut`	Yes
`truncated`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 9, 2026

TDQS

C2.9/5.0

Behavior3/5

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

The description adds genuine behavioral nuance: 'exitCode comes from the guest; a failing command is not an error.' This is valuable beyond the schema because it tells agents to treat a non-zero exit code as data, not failure. However, it does not explain stdout/stderr delivery, behavior for a stopped machine, or command serialization.

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 redundancy. The core action is stated in the first sentence, and the subtle exit-code behavior is given in the second. Every word contributes.

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

Completeness3/5

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

An output schema exists, so return values are not required in the description. The description captures the essential operation and the exit-code nuance, but gives no guidance on selecting this tool over siblings and no parameter hints. Not wholesale but has clear gaps.

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

Parameters2/5

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

The description offers no parameter-level information. Schema description coverage is only 57% (the schema covers env, command, target), so the description would need to add meaning for ambiguous parameters like stdin, workdir, and timeoutSecs, but it does not.

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 ('Run a command') and resource ('in a running machine'). This clearly separates it from machine creation/deletion tools, and the phrase 'running machine' distinguishes it from likely one-shot sibling 'run-once', though that distinction is implicit.

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

Usage Guidelines1/5

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

No guidance is provided about when to use this tool versus alternatives like 'run-once' or prerequisites such as 'machine must be running'. The description shows the intended context in passing but does not explicitly state when not to use the command.

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

Deploy Server