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Compose Preview Catalogs

by io.github.yschimke
OverviewDiscussionsAdmin

UI Builder

ui_builder_open

Open the UI Builder's design list: pick a design to see it as the editor draws it. Takes no arguments. Also opens from the ChatGPT/Codex sidebar, and a deep link to /design/ opens one design.

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": "ui_builder_open"
  }
}

Input Schema

NameRequiredDescriptionDefault
tokenNoA grant token from poll_access, when you cannot set the X-Compose-Preview-Token header yourself — an MCP client fixes its headers at connect time, so this is how a token approved during this session is used in it. Prefer the header where you control it.
agentNameNoOptional agent/client name shown to design viewers; self-reported.
agentModelNoOptional current model name shown to design viewers; self-reported. Omit when unknown.

Output Schema

NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changed
    • addedInput schema / properties / agentModel
      Added value: +{
+  "description": "Optional current model name shown to design viewers; self-reported. Omit when unknown.",
+  "maxLength": 80,
+  "type": "string"
+}
    • addedInput schema / properties / agentName
      Added value: +{
+  "description": "Optional agent/client name shown to design viewers; self-reported.",
+  "maxLength": 80,
+  "type": "string"
+}
  2. Added

TDQS

B3.2/5.0
Behavior3/5

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

No annotations exist, so the description carries the full burden. It does disclose genuinely useful behavior beyond the schema: this is a UI-opening/navigation action, not a data fetch, and it can be entered from the sidebar or a /design/<id> deep link. However, it omits any auth or session context even though a token parameter exists, and the claim 'Takes no arguments' is inaccurate against the schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose is front-loaded in the first clause, and the description is short with no padding. The one wasted-and-inaccurate sentence is 'Takes no arguments,' which costs it a point.

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?

An output schema exists, so return values need not be explained. But for a tool whose schema includes a session-grant token tied to poll_access, the description says nothing about the auth path and instead asserts there are no arguments, leaving an agent without guidance on the token parameter.

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

Parameters2/5

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

Schema description coverage is 100%, so the baseline would be 3. But the description's statement 'Takes no arguments' actively contradicts the schema, which defines three optional parameters (token, agentName, agentModel), and it adds no meaning about the token/auth flow the schema describes. Misleading param framing pushes this below the baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: 'Open the UI Builder's design list.' It also clarifies the follow-on behavior ('pick a design to see it as the editor draws it') and mentions the deep-link path. It does not explicitly distinguish itself from close siblings like ui_builder_view or ui_builder_list_designs, so it falls short of a 5.

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?

Usage is only implied: open the builder when you want to see designs as the editor renders them. The other sentences describe alternate entry points (ChatGPT/Codex sidebar, /design/<id> deep link) rather than when to choose this tool over ui_builder_view, ui_builder_list_designs, or ui_builder_get_design. No when-not guidance or explicit alternative is given.

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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