@uuup/mcp

Local-only MCP tools for deterministic text and structured-data processing. Version 0.1.0 is an npm-only developer preview for macOS and requires Node.js 22.12.0 or newer.

The server communicates only over local standard input/output. It has no Remote MCP, HTTP, SSE, Cloudflare, telemetry, update-check, hosted-service, or remote fallback mode.

Support matrix

| Client surface | macOS 0.1.0 status | Important boundary | | --- | --- | --- | | ChatGPT Desktop, Codex work surface | Verified | Uses the app-bundled Codex local runtime. This does not make the package available in ChatGPT Chat or Work. | | Claude Desktop, app-managed Code/Cowork surface | Verified | Uses Claude Desktop's managed local Claude Code runtime. This npm package is not a one-click Desktop Extension. | | Codex CLI | Verified | Local STDIO compatibility client. | | Claude Code | Verified | Local STDIO compatibility client. | | ChatGPT Chat/Work, web, or mobile | Not supported | These surfaces do not directly connect to this local STDIO package. UUUP will not add a Remote MCP fallback. | | Claude web or mobile | Not supported | Local MCP remains on the desktop or CLI host. | | Windows, Linux, and other clients | Not verified | Node compatibility alone is not a client-support claim. |

The verified versions and checksums are recorded in the UUUP repository's release evidence. Client behavior can change independently of this package; retest before relying on a newer client version.

Install and run

After 0.1.0 is published, use the exact version:

npx --yes @uuup/[email protected] --stdio

npx may contact the npm registry to download the package. Once installed, the UUUP process itself does not make business network requests.

For a conventional local install:

npm install --save-exact @uuup/[email protected]
./node_modules/.bin/uuup-mcp --stdio

The CLI also supports --help and --version. Unknown options fail closed; there are no network transport flags.

Client configuration

All examples pin 0.1.0 so that a client restart cannot silently change the server implementation.

Codex CLI and the Codex work surface in ChatGPT Desktop use a Codex MCP entry:

[mcp_servers.uuup]
command = "npx"
args = ["--yes", "@uuup/[email protected]", "--stdio"]

You can create the equivalent Codex CLI entry with:

codex mcp add uuup -- npx --yes @uuup/[email protected] --stdio

For Claude Code:

claude mcp add --scope user uuup -- npx --yes @uuup/[email protected] --stdio

For a local client that accepts the traditional JSON configuration shape:

{
  "mcpServers": {
    "uuup": {
      "command": "npx",
      "args": ["--yes", "@uuup/[email protected]", "--stdio"]
    }
  }
}

Configuration locations and user interfaces belong to each client and may change. In particular, adding this JSON to a legacy Claude Desktop file is not claimed to enable a traditional Claude Chat surface. Current Claude Desktop normally presents local integrations as Desktop Extensions; 0.1.0 remains an advanced npm preview.

Restart the client after changing its MCP configuration. Remove the uuup entry to uninstall it from the client. If you installed the package into a project, also run:

npm uninstall @uuup/mcp

To upgrade later, replace the pinned version deliberately and repeat client acceptance. Do not use an unpinned package name for a reproducible setup.

Tools

The server exposes exactly six read-only, deterministic tools:

| Tool | Purpose | | --- | --- | | analyze_text | Measure characters, words, lines, whitespace, and estimated reading time. | | normalize_text | Apply explicitly selected trim, repeated-space, empty-line, repeated-line-break, and Chinese punctuation-spacing rules. | | convert_markup | Convert Markdown to sanitized HTML or HTML to Markdown. | | validate_structured_data | Validate or convert JSON, YAML, and XML under strict parser and resource rules. | | build_seo_package | Build escaped meta tags and optional JSON-LD from explicit metadata. | | content_quality_gate | Check declared structural, readability, link, heading, and safety rules. |

Every successful protocol call returns the same result in structuredContent and compact JSON text content. The latter is a fallback for clients that do not expose structured tool results to the model.

Rule failures are normal results with isError: false; invalid arguments, resource limits, cancellation, timeout, and internal failures are tool errors. The server does not expose Tasks and does not perform background work.

Result limits and semantics

• Input frames are limited to 1 MiB before JSON parsing.
• Business text and structured inputs have per-tool limits between 32 KiB and 128 KiB; metadata and total arguments have stricter limits where required.
• At most one tool call runs and one is queued. A third call fails with SERVER_BUSY.
• The total deadline, including queue time, is 5 seconds.
• Worker execution uses Node resource limits. The frozen macOS budget is at most 96 MiB idle RSS, 192 MiB RSS with one running and one queued call, and 48 MiB loaded main-thread heap.
• Outputs are bounded. Issues are capped and report hasMoreIssues when applicable.
• Reading-time estimates use fixed defaults of 300 CJK characters per minute plus 200 Latin words per minute; they are planning estimates, not observed user behavior.

The tools validate only their declared structure, formatting, transformation, and content-safety rules. They do not browse, retrieve sources, or establish factual accuracy, truth, authorship, legality, originality, or SEO ranking. Treat generated SEO markup and quality-gate results as material for review.

Security and privacy

There are four separate data boundaries:

1. npm download: npm or npx may contact the configured registry and use its normal cache while installing the package.
2. UUUP process: runtime code processes only tool arguments from STDIO. It does not send content to UUUP or Cloudflare, read arbitrary files, clipboard/browser state, shell configuration, or environment variables for content, and does not write inputs, outputs, history, cache, or log files.
3. MCP client: the client starts the process and may retain configuration, conversations, tool arguments, or results under its own product behavior.
4. model provider: the client may send prompts, tool arguments, and tool results to its model service. Review that provider's privacy and retention terms; local MCP execution does not make the model local.

STDOUT is reserved for MCP protocol frames. Default diagnostics are limited, sanitized, and sent to STDERR only for fatal transport or CLI usage errors. Malformed JSON, YAML, and XML, unsafe markup or URLs, and bounded-resource failures do not return the complete original input in error messages.

The package intentionally has no install lifecycle scripts and no runtime npm dependencies. Its bundled JavaScript can be inspected. It does not contain UUUP TypeScript source files or source maps, but bundling is not a secrecy or security boundary.

Protocol and compatibility

0.1.0 uses the legacy initialize-based MCP opening and requires protocol revision 2025-06-18 or newer. It has been exercised with 2025-06-18 and 2025-11-25. Revisions at or below 2025-03-26 are rejected rather than silently widening the resource and batching contract.

License

UUUP-owned code is provided under the proprietary UUUP Free Use License 1.0. It permits free internal use by individuals and organizations, but prohibits redistribution, resale, relicensing, repackaging, hosted services, Remote MCP, SaaS, and competing products as described in the license. UUUP claims no ownership of your inputs or tool results.

Bundled third-party components retain their own licenses and notices in THIRD_PARTY_NOTICES.txt.