# Jernkorset Breve -- En brevsamling fra 1911-1918

> Probe-verified (tier 2 of 3). Last checked 2026-08-23. 3 of 5 capability checks passed.

- host: jernkorset.dk
- url: https://jernkorset.dk/
- category: historical letter archive
- type: education
- country: DK
- locations: Øster Aabølling, Sønderjylland, Denmark
- language: da

## Probe-verified · tier 2 of 3

Probed live on 2026-08-23 against rubric v1. 3 of 5 checks passed.

- PASS — Markdown negotiation
- PASS — Markdown twin at a predictable URL
- fail — llms.txt
- PASS — API catalog
- fail — MCP server answers

## Unverified actions

Read from the page's own content, with the wording each was drawn from. Inference is kept separate from tested facts; an agent completing the action is tier 3.

- **search** — "Fritekst-søgning i brevene" → `https://jernkorset.dk/search/`

## Summary

Archive of 665 letters from Peter Mærsk, a Danish soldier in German service during World War I, covering 1911 to 1918.

## Context

493 sites in this index share the type "education"; 284 are transactional.

## How we grade

- tier 1 — **Declared**: The site says agents are welcome in its robots.txt. A permission, not a capability.
- tier 2 — **Probe-verified** (this site): We fetched the site and tested each signal ourselves. Dated, repeatable, re-checked on a schedule.
- tier 3 — **Behaviourally verified**: An agent completed the action end to end — booked, bought, submitted — and it worked.

## About this record

Known-Good probes sites live and publishes what was tested and when.
Method: https://knowngood.sh/about.md · Rubric: https://knowngood.sh/benchmark