Skip to main content
Glama
Sign In
scratch-unified-mcp

scratch-unified-mcp

by blessed0x
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Local

Sb3 Vm Step Frame

sb3_vm_step_frame

Advance a Scratch project by one frame to get before/after states and delta, enabling precise state inspection.

Instructions

Step exactly one frame; returns before/after + delta. (proxied)

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": "sb3_vm_step_frame"
  }
}

Input Schema

NameRequiredDescriptionDefault

No arguments

Output Schema

NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.0.0

TDQS

A4.2/5.0
Behavior3/5

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

The description discloses that the call is proxied and that it reports before, after, and delta states, which is useful beyond the bare name. However, with no annotations, it does not state prerequisites such as a loaded VM or side effects on ongoing execution; 'step' only implicitly conveys mutation.

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?

A single front-loaded sentence states the action, the exact scope, and the return summary. The parenthetical '(proxied)' is the only extra marker and is informative rather than filler.

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

Completeness4/5

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

For a zero-parameter tool with an output schema, the description covers the action and the return concept. The only missing context is prerequisite state, such as whether the VM must already be loaded via sb3_vm_load, which is a minor gap for a simple stepping tool.

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 tool has zero parameters, so there is no parameter semantic burden on the description. The schema already covers the empty input fully, and the baseline for a zero-parameter tool is 4.

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 verb 'step' plus 'exactly one frame' identifies a precise, singular action and distinguishes it from sibling tools like sb3_vm_run and sb3_vm_run_until. The return summary adds further specificity without ambiguity.

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?

Clear context: this is the tool to use when the agent needs to advance exactly one frame rather than run continuously. It does not explicitly name alternatives or exclusions, but 'exactly one frame' makes the intended usage obvious among VM stepping siblings.

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

Deploy Server

Other Tools