DeepSeek Harness MCP Schema Calculator
Measure MCP tool-schema JSON locally and compare any catalog against MCP Lens.
About
The DeepSeek Harness MCP Schema Calculator is a browser-only MCP schema calculator that measures exact UTF-8 bytes of tool-schema JSON without uploading any data. Paste a DeepSeek Harness or other MCP tool-schema payload, and the page locally compares it against MCP Lens's fixed two-tool benchmark of 1,114 bytes. The tool detects accepted shapes like arrays of tools, objects with `tools`, `schemas`, or `header.tools`, and shows exact bytes, tool count, and reduction percentage. It also offers shareable links, Markdown, repro commands, and downloadable cards that never include your pasted schemas, only bounded numeric fields and a fixed self-reported label.
What is DeepSeek Harness MCP Schema Calculator
The DeepSeek Harness MCP Schema Calculator is a local in-browser MCP schema calculator that measures the exact UTF-8 byte size of JSON tool schemas and compares them against the MCP Lens benchmark. It runs entirely client-side: no upload, no API call, parsing and rendering happen only in your browser. You paste a DeepSeek Harness or generic MCP tool-schema JSON payload, and the tool computes canonical JSON.stringify(...) output bytes, detects model-visible tool count, and compares with MCP Lens's fixed two-tool surface of 1,114 bytes. It includes a standing schema example that drops from 674,249 bytes to 27,401 bytes, a tested completion result of 3/3 vs 3/3, and a pilot cost drop from $0.03072 to $0.00347. The page also provides a 1,000-tool sample and shareable claim boundaries.
Key features
- 100% local parsing: No files leave the browser; no API calls or telemetry.
- Exact UTF-8 byte calculation using canonical JSON.stringify(...) output.
- Accepted payload shapes: an array of tool objects, or an object containing
tools,schemas, orheader.tools/request.header.tools. - Comparison with MCP Lens component benchmark: 2 tools, 1,114 bytes at 1,000 tools.
- Show detected tools, exact bytes, reduction percentage, and current surface details.
- Share options: copy share link, Markdown, repro command, download card. Shared links and exports contain only bounded numeric fields and a fixed self-reported label—never the pasted schemas.
- Built-in samples: 1,000-tool sample and standing schema example.
- Numeric check catches accidental edits in shared links; it is not a cryptographic signature or proof of measurement.
How to use it
- Open the provided URL in any modern browser.
- Paste your DeepSeek Harness or other MCP tool-schema JSON into the textarea. The page accepts an array of tool objects or an object with
tools,schemas, orheader.tools/request.header.tools. - Click "Analyze locally" (or use the equivalent control) to run the calculation in your browser.
- Review the output: detected tools, exact UTF-8 bytes, MCP Lens surface (2 tools / 1,114 B), reduction percentage, and current surface details.
- Optionally load the 1,000-tool sample to see the catalog tax benchmark.
- Share results via copy share link, Markdown, repro command, or download card. Remember shared exports exclude the actual schemas.
Who it is for
- Developers integrating MCP tool schemas into DeepSeek Harness or similar model harnesses who want to understand per-turn context overhead.
- MCP tool catalog maintainers evaluating how many tools to expose to a model.
- Researchers measuring the "catalog tax" of large tool catalogs versus a minimal MCP Lens surface.
- Anyone who wants a private, no-install way to audit schema sizes before installing MCP Lens or other reduction utilities.
What to know before you use it
- Schema bytes are not tokenizer tokens, provider bills, latency, or task quality. The page measures only raw JSON byte size.
- The MCP Lens component benchmark is a fixed two-tool surface with 1,114 bytes checked into the repository; it is not a real-time measurement.
- Shared values are self-reported. The numeric check in links catches accidental edits but does not authenticate or independently verify that a measurement occurred.
- The live V4 Flash pilot mentioned in the repository is a separate three-task measurement with explicit dates and caveats; this page does not reproduce or extend that pilot.
- The tool never uploads your schemas. However, if you share a link or export, you may publish the bounded numeric fields you choose to share.
- Use an official MCP or DeepSeek source for tokenizer-specific context limits, billing, or compliance needs; this calculator is a local byte-size diagnostic.
In short, the DeepSeek Harness MCP Schema Calculator is a pragmatic MCP schema calculator for local JSON size auditing; while it does not replace official tokenizer or billing tools, it gives developers a fast, private way to quantify catalog tax before making integration decisions.
FAQ
Is MCP Lens Catalog Calculator free to use?
Yes, it appears to be free to use in the browser. The page does not show a price, sign-up gate, or paid plan in the source material.
Is the DeepSeek Harness MCP Schema Calculator free to use?
Yes, it is a free browser-based tool with no sign-up or payment. It runs entirely locally in your browser, so there are no usage fees or credits required.
Does it upload my MCP schemas to a server?
No, it says parsing and rendering happen locally in your browser only. The site also states there is no upload and no API call.
Does it upload my MCP schemas anywhere?
No, the calculator runs completely in your browser. Parsing and byte calculation happen locally, and the page never sends your pasted JSON to a server. Share links and exports include only numeric fields and a fixed label, not your original schemas.
What kinds of JSON payloads can I paste?
It accepts an array of tool objects or an object with `tools`, `schemas`, `header.tools`, or `request.header.tools`. That makes it flexible for different MCP-shaped outputs.
What JSON shapes does the calculator accept?
It accepts an array of tool objects, or an object containing `tools`, `schemas`, or `header.tools` / `request.header.tools`. Other shapes will not be detected correctly by the local parser.
What does the byte count actually measure?
It measures exact UTF-8 bytes from canonical `JSON.stringify(...)` output. It does not claim to measure tokens, provider cost, latency, or model quality.
How does the MCP Lens comparison work?
The tool compares your pasted payload's exact UTF-8 byte size and tool count against MCP Lens's checked-in benchmark of 2 tools and 1,114 bytes at 1,000 tools. It calculates a reduction percentage and shows both surfaces side by side.
Who should use this app?
It is best for AI builders, developer-tooling teams, and researchers who need a quick local check on schema size. It is less useful if you need hosted storage or audited team analytics.
What does the byte measurement actually count?
It counts the length of the canonical JSON.stringify(...) output in bytes, as computed in your browser. It does not measure tokenizer tokens, API costs, latency, or output quality.