The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the Secret MCP listing page.
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An evidence-grounded MCP server for web design analysis, screenshot-to-specification workflows, and frontend reconstruction planning.
Secret MCP is a local Model Context Protocol (MCP) server that searches GDWEB for recent design references and creates a separate LLM request and a separate DESIGN_INDEX file for every search result. Each file contains page- and route-specific layouts, navigation, pixel coordinates, colors, components, and responsive specifications traceable to the supplied visual evidence.
The name Secret MCP does not mean that the project provides secret features or private data. It was the project name used while experimenting in a private repository with the idea of building an MCP server around design websites. The project's current purpose is to extract reproducible structural evidence from public design references and turn it into one specification per work that an LLM can apply to a new project.
Images and descriptions from multiple works are never combined in a single LLM context or document. The server processes search results sequentially inside the server, creates an independent MCP sampling/createMessage request for each work, saves that work's file, and only then advances to the next work. A separate local web application lets you select one work at a time, inspect its source evidence, measured colors and coordinates, LLM contract, generation log, and final document, and manage the exclusion list for subsequent searches.
Evidence-Isolated Multimodal Design Analysis through MCP Sampling
Working paper and implementation report · Secret MCP v0.6.0 · not peer reviewed
Secret MCP implements an auditable pipeline for converting public webpage screenshots into implementation-oriented design specifications. The system prepares desktop and mobile visual evidence, records crop coordinates and representative pixel colors, and invokes client-side MCP sampling once per reference. Unlike workflows that concatenate several design references into one prompt, Secret MCP treats reference identity as both a request boundary and an artifact boundary: one reference produces one sampling request, one request contract, and one DESIGN_INDEX document. Each request asks for includeContext: none and applies the same 19-section specification contract covering routes, geometry, components, design tokens, responsive behavior, accessibility, implementation tasks, acceptance criteria, and uncertainty. This report evaluates protocol-level isolation and artifact production; it does not claim that one language model, prompt, or reconstruction method outperforms another. A live smoke test verifies the request boundary, while a preserved three-reference run provides descriptive measurements and a qualitative implementation case.
| Question | Current evidence | Status |
|---|---|---|
| RQ1. Can an MCP design-analysis tool maintain one-reference-per-request isolation? | Live sampling smoke test with cross-reference ID inspection and output-file checks | Verified within the test scope |
| RQ2. Can screenshot evidence be transformed into auditable spatial, color, and document artifacts? | Preserved three-reference run with evidence manifests, contracts, and generated documents | Descriptively verified |
| RQ3. Can the resulting specification guide a distinct frontend implementation? | AEROFLOW qualitative case study | Preliminary; no controlled comparison |
For reference r_i, the prepared evidence set contains image tiles I, crop bounds B, representative-color measurements P, and source metadata M. The fixed specification contract is C; the independent request and resulting document are q_i and D_i.
Coordinates measured inside a prepared tile map back to the original screenshot as follows.
This is an operational isolation invariant, not a claim of statistical independence. The server and smoke test can inspect request contents and artifacts; they cannot prove what an arbitrary external model provider may retain outside the MCP message.
| Sampling request | gdweb-26522 present | gdweb-24516 present | Output documents |
|---|---|---|---|
| Request 1 | 1 | 0 | 1 |
| Request 2 | 0 | 1 | 1 |
Figure 1. Live smoke test recorded on 2026-08-22 using the query 금융 (n = 2 sampled references after excluding gdweb-26905). Each request contained its own reference ID and visual evidence, no other sampled reference ID, and includeContext: none; the run produced two distinct Markdown files. The test verifies observable request composition and file separation, not model-memory behavior outside the protocol.
| Reference | Desktop source height | Prepared images | Image payload | Color measurements | Document tokens | Document size | Required headings |
|---|---|---|---|---|---|---|---|
gdweb-27294 | 2,675px | 3 | 126.6KB | 24 | 7,921 | 54.0KB | 19/19 |
gdweb-25378 | 7,043px | 4 | 302.5KB | 32 | 9,953 | 69.8KB | 19/19 |
gdweb-24234 | 7,832px | 5 | 387.8KB | 40 | 9,517 | 63.2KB | 19/19 |
Figure 2. Descriptive measurements from preserved run 2026-07-29T15-54-10-483Z-5c70317e (n = 3 references). The run prepared 12 evidence images totaling 816.9 decimal KB and recorded 96 representative-color measurements. It produced three DESIGN_INDEX documents totaling 27,391 whitespace-delimited tokens and 187.0 decimal KB. All three contain headings 1–19; heading presence does not establish semantic correctness.
| (a) Evidence and measurements | (b) Per-reference DESIGN_INDEX | (c) Specification-driven implementation |
|---|---|---|
![]() | ![]() | ![]() |
Figure 3. A preserved qualitative trace from the GDWEB evidence viewer to the generated Korean Air DESIGN_INDEX and then to AEROFLOW. AEROFLOW intentionally introduces new branding, content, imagery, and functionality; this example illustrates specification use and is not a controlled visual-fidelity comparison.
n = 2; the recorded artifact analysis has n = 3. Neither supports broad claims about design quality or model performance.Node.js 20.19 or later is required.
The published MCP server can be launched with:
Clone the repository when you also need the local viewer or want to work on the source:
Set DESIGN_INDEX_OUTPUT_DIR to the same value for the MCP server and the web application so that both processes read the same output directory.
Open the following address in a browser.
The web application displays the generation-run list, per-work progress, GDWEB evidence images, measured coordinates and palettes, the specification contract sent to the LLM, the final Markdown, and generation timestamps. Documents and evidence are read-only; only Exclude from search and Remove exclusion change the filter used by subsequent searches.
For a source checkout, replace command and args with "command": "node" and "args": ["/absolute/path/to/secret_mcp/dist/index.js"].
The MCP client must support sampling/createMessage. When a client does not support sampling, the server returns an explicit error instead of running a fallback that places multiple works in the same context.
The MCP stdio server itself does not open an HTTP port. The client launches node dist/index.js as a child process and exchanges JSON-RPC messages over stdio. Only the separate web viewer process uses port 4317 by default.
The server does not need to be modified when the outer MCP host cannot answer sampling/createMessage. A separate MCP protocol client can connect directly to dist/index.js, advertise sampling: {}, and handle every sampling request by launching a fresh Codex LLM process in a fresh temporary workspace.
The sampling handler must copy only the current request's text blocks and evidence images into that workspace. It must not reuse a Codex conversation, process, working directory, response file, or message history from another work. The workspace launches one new Codex process, waits for its complete Markdown response, returns that response to the pending MCP sampling call, and can then be removed after the server has saved the work's contract, evidence, and document.
The server still controls the sequential queue: work 2 is not prepared until work 1 has returned and been saved. This makes the fresh process and workspace an execution-level equivalent of the protocol-level includeContext: none boundary without adding a combined fallback to the server. The direct client becomes the sampling-capable MCP host; it should use a tool-call timeout long enough for the per-work output budget and must never answer multiple sampling requests through one persistent LLM conversation.
A separate /web-design slash command is not required.
The host LLM calls the generate-gdweb-design-indexes tool once. The MCP server performs the search and separates the per-work LLM requests internally.
The manual tool-call format is shown below.
If outputDirectory is omitted, the tool uses the DESIGN_INDEX_OUTPUT_DIR environment variable. If that variable is also absent, it uses the design-index directory under the server's working directory.
maxTokens is a per-work output budget, not a budget shared by the run and not a budget divided equally between pages. A single work may contain multiple visible pages or routes, and every page must repeat the complete page-specific parts of the 19-section contract. The default and minimum are therefore 131072 tokens. Clients may request up to 262144 tokens for exceptionally large multi-page evidence sets.
With limit: 3, the default run can request up to three independent 131072-token outputs; the works do not share one 131072-token pool. The connected sampling client and selected model must support the requested output size. If the model returns stopReason: maxTokens, the server treats that work as failed instead of saving a truncated DESIGN_INDEX as complete.
When the tool completes, it returns the run ID, run-manifest path, per-work document paths, and web-viewer URL.
For the actual example, Secret MCP found three aviation award winners registered on GDWEB in 2026 and 2025, created a DESIGN_INDEX for each work through an independent LLM request, and then applied the structure of the Korean Air reference to a Godot aviation project website.
The finished AEROFLOW website is not a clone of the Korean Air website. It uses the information hierarchy, navigation, action panel, section arrangement, and responsive principles from the specification while introducing a new brand, copy, aviation imagery, and content. This example demonstrates that even when the resulting design differs from the reference, measurable structural evidence can still produce a polished website with a distinctive identity.
After starting the processes, open the following screens.
Select works one at a time from the run list on the left. The right side displays only the final DESIGN_INDEX for the selected work, without mixing in content from other works.

The Evidence tab shows the desktop and mobile images sent to the independent LLM request, tile coordinates, reduction ratios, and representative colors.

The Request Contract records page separation, navigation, section bounds, HEX/RGB/HSL colors, components, the responsive matrix, and acceptance criteria. This contract prevents the result from ending as a superficial mood summary and makes it an implementation specification another LLM can use.

The Generation Log shows the sequence from search and evidence preparation through the independent per-work LLM request, document save, and full-run completion. This run processed all three works with separate includeContext: none requests.

The bright aviation portal and action-panel structure observed in the Korean Air reference were adapted to a Godot project. The brand, aircraft imagery, copy, and functionality were created specifically for this result.

The reservation and promotion card structure was repurposed for core project content: flight regions, a glass cockpit, and real-time weather.

The source reference's notices and service shortcuts were restructured into build history, development progress, flight models, avionics, media, controls, and roadmap navigation.

The final area contains project media, development, support, and license links, followed by an independent-project footer.

These links point directly to the actual files included in the repository. The same artifacts are also grouped under tmp/showcase/aviation-godot through relative symbolic links for local execution and browsing.
The following boundaries are essential.
limit: 3, the server performs exactly up to three mutually independent LLM sampling requests.includeContext: none.In other words, this is not the earlier architecture in which the host LLM reads every result at once and produces a combined summary.
The web viewer reads DESIGN_INDEX_OUTPUT_DIR/.secret-mcp-runs every 2.5 seconds. There is no separate database or debugging connection between the MCP generation process and the web server.
The interface contains the following areas.
gdweb-<work-number>When a run contains three works, it also produces three documents as shown below.
run.json is not a file that combines document bodies from multiple works. It is a viewer manifest containing only per-work file paths, status, timestamps, model, and evidence lists.
Selecting Exclude from search in the web viewer saves the work number to the following file.
generate-gdweb-design-indexes and search-gdweb-designs runs filter work numbers before selection.limit from the non-excluded works.Remove exclusion makes the work eligible again starting with the next search.DESIGN_INDEX_OUTPUT_DIR to share the same exclusion list.GDWEB's full desktop captures can be extremely tall and several megabytes in size. Sending the original base64 data directly in a sampling request can exceed MCP transport limits or cause a vision model to miss fine structural details.
Before creating the request for each work, gdweb-sampling-images.ts performs the following operations.
sgbn=1sgbn=3x/y/width/height coordinates, source-space coordinates, and source URL for every tileMultiple tiles from one work are included in the same work-specific sampling request. Tiles from different works are never included in the same request.
Representative colors are measurements sampled from normalized screenshot pixels. They are precise evidence for visual comparison, but they must not be presented as the source site's CSS variables because JPEG error and image content affect the values. The generation contract distinguishes MEASURED colors from INFERRED implementation tokens.
The server does not open the work's live production website or crawl its DOM. Visual evidence is limited to the images and metadata registered on GDWEB.
Design search does not use browser automation, Bing, Brave, or DuckDuckGo.
year is omitted, the current runtime year is used.includePreviousYear defaults to true.includePreviousYear: false, only the target year is allowed.awardOnly defaults to true, so works without an award name are excluded.limit can be set from 1 through 10.| Field | Description |
|---|---|
strNo | GDWEB work number, also used in the document filename |
txtFgbn | GDWEB work-category value |
title | Work title |
gdwebUrl | GDWEB work detail page |
registeredDate / registeredYear | Registration date and the year used for filtering |
award | Award name |
concept | Design concept |
primaryColor | Primary color |
productionCompany | Production company |
desktopImageUrl | GDWEB desktop capture (sgbn=1) |
mobileImageUrl | GDWEB mobile capture (sgbn=3) |
Every independent sampling request includes the secret-mcp/design-index/v2 contract. The resulting filename is DESIGN_INDEX_gdweb-<strNo>.md.
There is one file per work, but each file begins with a page and route inventory and repeats a complete subsection for every verified page. The contract does not mistake sections in a long scrolling capture for separate pages; it splits pages only when the evidence collage visibly contains separate screens.
Every document must contain all 19 numbered sections below.
| Area | Required Specification |
|---|---|
| Reconstruction goal | Reference ID, target fidelity, routes, target viewports, and non-goals |
| Evidence and coordinate system | Image IDs, original/prepared dimensions, scale, tile coordinates, source-space coordinates, and overlap-removal method |
| Site map | Verified pages and routes, purpose, evidence images, shared shell, active menu, and confidence |
| Shared app shell | Global background, container, gutters, overlays, page chrome, and stacking context |
| Navigation | Desktop and mobile heights, logo/menu coordinates, gaps, touch areas, and active/hover/focus/open states |
| Per-page specification and coordinate table | Canvas model, section order, x/y/width/height, layout, states, data, and evidence level for every page |
| Layout deep dive | DOM, grid/flex, tracks, min/max, ratios, gaps, overflow, sticky, absolute, and z-index |
| Component abstraction | Page-linked component tree, props, variants, slots, state, events, and data contracts |
| Tokens and exact colors | HEX/RGB/HSL/alpha, usage, measurement coordinates, confidence, tolerance, and CSS variables |
| Typography | Font family by role, px/rem, weight, line height, letter spacing, alignment, truncation, and responsive values |
| Assets and icons | Page and section, display size, aspect ratio, crop, focal point, object-fit, loading, and fallback strategy |
| Responsive matrix | Containers, columns, order, visibility, navigation, and spacing at 1440/1280/1024/768/390/360px |
| Interaction and motion | Color, opacity, transform, duration, easing, keyboard, and reduced-motion behavior for every state |
| Accessibility | Per-page landmarks, headings, focus, menu semantics, labels, alt text, contrast, and touch targets |
| Data and content | Page entities, fields, counts, ordering, formats, localization, and loading/empty/error fixtures |
| Frontend architecture | Routes, directories, page/shared modules, tokens, assets, state, and server/client boundaries |
| Implementation task graph | Measurement, shell, navigation, per-page task IDs, dependencies, deliverables, and completion criteria |
| Per-page acceptance criteria | Coordinate, color, and typography tolerances; viewport comparison; overflow; assets; keyboard; and performance |
| Uncertainties and decisions | Per-page and per-section UNKNOWNs, adopted values, alternatives, confidence, and additional evidence required |
Every major judgment is marked with one of the following evidence levels.
OBSERVED: directly visible in a GDWEB image or metadataMEASURED: numerically verified from supplied pixel coordinates or the measured paletteINFERRED: reasonably inferred to reproduce the same resultUNKNOWN: cannot be verified from static evidence and must not be asserted as factAnother LLM must be able to derive the component tree, tokens, responsive rules, assets, implementation order, and validation items from the completed document alone.
The server currently exposes five MCP tools.
| Tool | Purpose |
|---|---|
generate-gdweb-design-indexes | Search GDWEB, make an isolated LLM request per result, and save documents |
search-gdweb-designs | Return a GDWEB reference list without generating specifications |
full-web-search | Search the general web and extract full page content |
get-web-search-summaries | Return titles, URLs, and descriptions from a general search |
get-single-web-page-content | Extract the full content of a known general webpage |
Use generate-gdweb-design-indexes for design planning, layout analysis, implementation specifications, and DESIGN_INDEX requests. Use search-gdweb-designs only for lightweight list requests.
The isolation smoke test connects a mock MCP client that supports sampling and verifies the following behavior.
includeContext: none.| Name | Default | Description |
|---|---|---|
DESIGN_INDEX_OUTPUT_DIR | ./design-index | Directory where generated documents are stored |
SECRET_MCP_WEB_ORIGIN | http://127.0.0.1:4317 | Web-viewer address included in MCP results |
SECRET_MCP_WEB_HOST | 127.0.0.1 | Web-server bind address |
SECRET_MCP_WEB_PORT | 4317 | Web-server port |
MCP_SAMPLING_TIMEOUT_MS | 1800000 | Timeout for each independent per-work LLM request in milliseconds |
MAX_CONTENT_LENGTH | 500000 | Maximum page-body length extracted from a general webpage |
DEFAULT_TIMEOUT | 6000 | Timeout for general HTTP and browser requests |
MAX_BROWSERS | 3 | Maximum number of browsers used for general extraction |
BROWSER_TYPES | chromium,firefox | Browsers used for general search and extraction |
BROWSER_HEADLESS | true | Whether Playwright runs headlessly |
FORCE_MULTI_ENGINE_SEARCH | false | Whether to compare every engine during general search |
DEBUG_BROWSER_LIFECYCLE | false | Whether to print browser lifecycle logs |
Secret MCP is positioned as an implementation artifact adjacent to multimodal UI understanding and screenshot-to-code research. It has not yet been evaluated on the datasets or metrics used by the papers below, so their results must not be interpreted as Secret MCP results.
sampling/createMessage, including request messages, model preferences, token budgets, and context controls. SpecificationSecret MCP is currently software with a working research note, not a peer-reviewed publication.