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mcp-screen

mcp-screen

by ashark-ai-05
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TypeScript
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list_canvases

Lists named canvases, one per project, so you can see available canvases before switching with open_canvas or targeting widgets.

Instructions

List named canvases (one per project). The default name is the git root folder. Switch with open_canvas; place_widget takes an optional canvas argument.

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_canvases"
  }
}

Input Schema

NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv0.1.1

TDQS

A4.2/5.0
Behavior3/5

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

No annotations are provided, so the description carries the full burden. It correctly implies a read-only enumeration and adds useful domain behavior (one canvas per project, default name = git root folder), but never states the return shape (list of names? objects?) and has no output schema to fall back on.

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?

Three compact sentences, each earning its place: purpose, naming rule, and cross-tool routing. Purpose is front-loaded with no filler or restatement of the name.

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, read-only listing tool with no annotations or output schema, the description covers what it returns conceptually and how it relates to open_canvas and place_widget. Only the exact return format is unspecified, a minor gap for such a simple 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 takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The mention of place_widget's optional canvas argument is contextual framing rather than parameter documentation for this 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?

States a specific verb and resource ('List named canvases') and immediately defines the unit ('one per project'), which disambiguates it from read_canvas and other canvas siblings. The default naming rule gives the agent a concrete mental model of what the results are.

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?

Names the complementary tool ('Switch with open_canvas') and explains that place_widget accepts an optional canvas argument, which implies this tool is the discovery step before either. It does not state an explicit when-not condition, but the sibling relationship is clear.

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

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