MCP.Market

Lens MCP server

by mrhpython·io.github.mrhpython/lens-mcp·v1.1.1
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Outside-in validation gate for AI-generated text; a separate model checks LLM output, fail-closed.

B83/100grade B
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Safety scan
B83/100

full report

Adoption
Growing

0 stars46 downloads/wk

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If you have run it, two minutes of your experience saves the next person an afternoon.

Lens tools (9)

write = sends, deletes, buys or posts

Read from the package source without running it. The installed server may list more.

  • lens_catches_add

    Append a NAMED DEFECT to the defect bank so it is caught next time. Record what was WRONG, the general pattern it is an instance of, and the forward rule that prevents it — doctrine REJECTS routine passes, so only log actual defects. Set self_catch=true when the defect was a failure of your own validation discipline. This is the write half of the improvement loop: enough recurrences of a pattern p

  • lens_catches_relevant

    Read the defect bank BEFORE validating: prior named defects for an artifact type, most-recurrent patterns first. This is the institutional memory that makes the gate improve over time — the recurring traps tell you where this class of artifact has failed before. Any pattern at threshold is marked [PROMOTE], meaning it recurs often enough to deserve a deterministic check. Runs the local lens-kit CL

  • lens_catches_stats

    Per-pattern recurrence counts across the defect bank. Any pattern at or above the threshold gets a PROMOTE-to-deterministic-check suggestion — that is the signal a recurring judgment call should become a cheap fixed check instead. Use this to decide what to harden next.

  • lens_consistency_leaks
  • lens_consistency_markers

    Check that evidence markers counted in a source artifact survive into every rendered output. Deterministic, no LLM, exit 6 on a violation. Catches the caveat, citation or hedge that gets dropped between formats — the source says 'as-of 2026-04' and the rendered deck quietly does not. Matching is CASE-SENSITIVE (unlike lens_consistency_leaks, which is case-insensitive), so pick markers whose casing

  • lens_consistency_numbers

    Check that every numeric literal in a summary actually appears in the body it summarizes. Deterministic, no LLM, exit 6 on a violation. Catches the invented figure — the number a summary asserts that its source never stated. TRIPWIRE, not an oracle: literal matching only, no semantic or derived arithmetic, so a legitimately computed total will flag. Review a hit, do not auto-trust it.

  • lens_health

    Check if the Soulfield Lens API service is running and responsive. Returns status and version. No auth required.

  • scrub_pii
  • validate_content

Public scan report

scanner v0.1.10 · 2026-10-30 · same rubric, same numbers if you re-run it

no findings
  • Code scan2 source files scanned25/25
  • –Live reliabilityno gateway calls yet and no remote to proben/a
  • –Tool poisoningtools not inspected (local package is not executed); not countedn/a
  • Auth qualitystatic API keys via environment variables6/15
  • Maintenancelast push 11 days ago15/15
  • Maintainer identityregistry namespace matches repository owner; GitHub account older than a year8/10
Overall 83/100. Components that don't apply are left out of the denominator. Any critical finding is an F.RubricAppeal a findingJSON

How Lens compares

Against every graded AI and agents MCP server, from our own scans and uptime checks. Updated after each scan run.

Safety score
83/100
higher than 68% of 4,460 AI and agents servers
Tools
9
the typical AI and agents server has 6
Tools that change things
0%
typical: 0%. Fewer write tools means less an agent can break
Downloads a week
46
more than 38% of 1,538 AI and agents servers with a package

What its tools let an agent do: 9 read

Install Lens in Claude Code, Cursor or VS Code

Runs npx -y @soulfield/lens-mcp on your machine. Read the scan report first; the gateway never runs local packages.

claude mcp add lens-mcp -- npx -y @soulfield/lens-mcp
Add to Cursor

What the publisher says

From the Lens repository's README, as published. We do not edit it. Read it on GitHub

Soulfield Lens — MCP server

Outside-in validation for AI-generated text, as an MCP tool.

Every AI tool asks the same model that wrote the answer whether it's any good. It says yes. The Soulfield Lens is outside-in: a separate model runs a fixed gate over your output. It checks text — it doesn't write it. This package puts that gate inside Claude Code, Cursor, and any other MCP-compatible agent, so output can be validated on the path where it's generated.

The gate is fail-closed: a borderline case returns UNKNOWN, never a silent pass. There is no generation step, so it can't fabricate claims of its own — only check. It can still be wrong about a judgment; that is exactly why borderline cases return UNKNOWN instead of a confident yes.

This is a thin stdio wrapper around the hosted Lens API (api.soulfield.one). No local model, no build step — one file, two dependencies.

It exposes two tiers. The gate tier (3 tools) needs nothing but an API key. The validator tier (6 tools) is optional and only activates if you also have the lens-kit CLI installed locally — it runs deterministic cross-file checks and the defect memory that the single-document gate cannot see. Skip it and the gate tier works exactly as before.

Try it before you install anything

The keyless demo endpoint runs the same gate — a few runs a day per IP, no signup:

curl -s https://api.soulfield.one/v1/demo \
  -H 'content-type: application/json' \
  -d '{"text": "<paste the AI output you are about to ship>"}'

Install

npm install -g @soulfield/lens-mcp

Or run without installing: npx @soulfield/lens-mcp.

Claude Code

claude mcp add soulfield-lens \
  -e SOULFIELD_API_BASE=https://api.soulfield.one \
  -e SOULFIELD_API_KEY=<your-key> \
  -- npx @soulfield/lens-mcp

Any MCP client (JSON config)

{
  "mcpServers": {
    "soulfield-lens": {
      "command": "npx",
      "args": ["@soulfield/lens-mcp"],
      "env": {
        "SOULFIELD_API_BASE": "https://api.soulfield.one",
        "SOULFIELD_API_KEY": "<your-key>"
      }
    }
  }
}

Production calls need an API key — request one at hello@soulfield.one. lens_health works without one.

Tools

Gate tier — hosted API, works out of the box

Validator tier — optional, requires the lens-kit CLI locally

Version note: the validator tier lands in 1.1.0. If npm view @soulfield/lens-mcp version still reports 1.0.0, the registry has not caught up with this repo yet and npx @soulfield/lens-mcp will give you the three gate-tier tools only. Install from source in the meantime.

Side effect worth knowing: every validator-tier call appends a row to RUNS.md in its working directory — that is the kit's run ledger, by design. The directory is the cwd argument, or the server's own cwd if you omit it, so pass cwd explicitly if you care where the ledger lives. Sensitive flag values are redacted in the row (--deny ), so deny terms do not land on disk.

Shortened. The full README is on GitHub.

Nothing above is checked by us. What we check is on the safety report.

Lens: common questions

Is Lens MCP server safe?
Mostly: it is graded B (83/100). Read the Lens safety report
How do I install Lens?
It runs on your machine. Copy the Claude Code, Cursor, VS Code or Claude Desktop config from the install section.
Does Lens need an API key?
Yes. The registry entry asks for SOULFIELD_API_KEY.
Is Lens maintained?
The last commit was 15 days ago (2026-10-19). The latest release is v1.1.1.
What can I use instead of Lens?
Servers from other publishers that do the same job: LLM Sandbox MCP server, PaperBanana MCP server and Decionis Commerce Gate MCP server.
How does Lens compare with other AI and agents MCP servers?
safety score 83/100 (higher than 68% of 4,460 AI and agents servers); tools 9 (the typical AI and agents server has 6); tools that change things 0% (typical: 0%. Fewer write tools means less an agent can break). Full comparison.

Alternatives to Lens

Same job from other publishers: the closest match first, then the best rated.

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    A
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  • llmtrim
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