stitch-bridge

generate_variants

Generate 1-5 design variants of an existing screen, returning HTML for each. Use natural language to specify desired changes and receive ready-to-use screen variants.

Instructions

Generate 1-5 design variants of an existing screen. Returns array of screen IDs and HTML.

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": {
      "projectId": "<projectId>",
      "screenId": "<screenId>",
      "prompt": "<prompt>"
    },
    "name": "generate_variants"
  }
}

Input Schema

Name	Required	Description
`count`	No	Number of variants (1-5, default: 3)
`prompt`	Yes	Variant generation prompt
`modelId`	No	Model to use
`screenId`	Yes	Source screen ID to create variants from
`projectId`	Yes	Project ID
`deviceType`	No	Target device type

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 10, 2026

TDQS

A3.7/5.0

Behavior3/5

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

With no annotations, the description carries the full burden. It discloses the output format ('array of screen IDs and HTML') and implies creation of variants, but it does not mention side effects such as persistence, permissions, potential costs, or rate limits. This is partial transparency, not comprehensive.

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 consists of two short, front-loaded sentences. It states the purpose first and then the output format, with no unnecessary words or repetition.

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?

Given the tool's complexity (6 parameters, no annotations, no output schema), the description covers the core purpose and output but lacks usage context and behavioral detail. The schema is rich, which compensates, but the description remains minimal and would benefit from mentioning side effects or differentiating from alternatives.

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 provides descriptions for all six parameters (100% coverage), so the description adds no additional parameter semantics. The baseline of 3 is appropriate because the schema already does the heavy lifting.

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 uses a specific verb ('Generate') and resource ('design variants of an existing screen') that clearly states what the tool does. This distinguishes it from sibling tools like generate_screen (creating a new screen) and edit_screen (modifying an existing one).

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 when to use the tool by specifying 'existing screen', which indicates a prerequisite, but it does not explicitly name alternatives or state when not to use it (e.g., for new screens use generate_screen). The context is present but not fully elaborated.

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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