ui-registry-mcp

Compare a component across libraries

compare_components

Compare component implementations across libraries. For a component intent, fetch the best match from each registry and view dependencies, file count, lines of code, install command, and source preview side by side.

Instructions

For a given intent (e.g. 'pricing table', 'date picker'), fetch the single best match from EACH library and return them side by side: dependencies, file count, lines of code, install command, and a source preview. Use this to choose the nicest implementation instead of taking the first search hit.

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": {
      "query": "<query>"
    },
    "name": "compare_components"
  }
}

Input Schema

Name	Required	Description	Default
`query`	Yes	The component intent, e.g. 'pricing table'
`registries`	No	Optional subset of registry ids to compare (default: all)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 10, 2026

TDQS

A4.7/5.0

Behavior4/5

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

No annotations provided, but the description details what the tool returns (dependencies, file count, lines of code, install command, source preview). It is implied to be a read-only fetch and compare, but could explicitly state lack of side effects.

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, efficiently conveying purpose, output, and usage guidance. Every word adds value; no redundancy.

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

Completeness5/5

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

For a tool with 2 parameters and no output schema, the description provides complete context: what it does, what it returns, and when to use it. No gaps.

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?

Schema coverage is 100%, so the schema already documents both parameters. The description adds value by clarifying 'query' as component intent and 'registries' as optional subset of registry ids, enhancing understanding.

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 compares components across libraries for a given intent, with examples like 'pricing table'. It distinguishes from siblings by contrasting with 'taking the first search hit' from search_components.

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

Usage Guidelines5/5

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

Explicitly says when to use: to choose the nicest implementation instead of taking the first search hit. This provides clear usage context and differentiates from search_components.

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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