mcpx

shell_spawn

Start a persistent local PTY session for interactive command execution. Returns a session ID for use with session_send and session_recv.

Instructions

Start a persistent local PTY session; returns a session id.

Drive it with session_send / session_recv.

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": "shell_spawn"
  }
}

Input Schema

Name	Required	Description	Default
`command`	No
`cols`	No
`rows`	No
`cwd`	No
`env_json`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0May 19, 2026

TDQS

B3.3/5.0

Behavior2/5

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

No annotations provided, so description carries full burden. It mentions 'persistent' and 'local PTY session', but lacks details on resource cleanup, auth requirements, or state management. Minimal behavioral disclosure.

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?

Extremely concise with two sentences. First sentence states the primary action; second sentence directs usage. No wasted words.

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

Completeness2/5

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

Despite having 5 parameters and no output schema details, the description ignores parameter semantics and return format. It mentions session_id but not its type or structure. Incomplete for effective tool selection and invocation.

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

Parameters1/5

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

Schema description coverage is 0%. The description adds no information about any of the 5 parameters (command, cols, rows, cwd, env_json) beyond what the schema provides (defaults and types).

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 tool starts a persistent local PTY session and returns a session id. It distinguishes from siblings by specifying that it is driven by session_send/session_recv, implying persistence.

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

Usage Guidelines4/5

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

Explicitly says to drive the session with session_send/session_recv, providing clear workflow context. However, no mention of when not to use this tool versus alternatives like shell_exec.

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

Deploy Server