{
 "schema": "csoai.measurement-capsule-batch/0.2",
 "as_of": "2026-09-26T06:43:21Z",
 "capsule_schema": "csoai.measurement-capsule/0.2",
 "adapter": "tool_drift",
 "kind": "measurement.tool_drift",
 "n_capsules": 3240,
 "states": {
  "UNCHANGED_AT_NAME_GRANULARITY": 1485,
  "UNCHECKABLE": 1755
 },
 "merkle_root": "fd0f514e03dd825698a3eab57d33431b09e62e442f85c7592db50f2371e9d2df",
 "merkle": "RFC 6962 Merkle Tree Hash over the capsule_id leaves (32 bytes each) sorted ascending: leaf = SHA-256(0x00 || capsule_id), node = SHA-256(0x01 || left || right); for n > 1 leaves the split is at k = the largest power of two smaller than n (RFC 6962 section 2.1), so no leaf is promoted or duplicated; one leaf = its leaf hash; empty = SHA-256 of the empty string",
 "canonicalisation": {
  "rule": "JSON, object keys sorted, no insignificant whitespace, UTF-8, non-ASCII unescaped; every capsule's bytes are checked byte-equal to its RFC 8785 (JCS) serialisation at build and at verify",
  "jcs_byte_equal": "3240/3240",
  "checked_with": "rfc8785 0.1.4 (independent RFC 8785 implementation)"
 },
 "capsules_file": {
  "path": "capsules.jsonl.gz",
  "sha256": "febe9aed6140c3cc12a0c256fb0ffa9e76bc66a19342f086af03ee60c7baa7aa",
  "bytes": 646582,
  "uncompressed_sha256": "5b30e6e8da77f8e181f0c8494dd3980837265776cc881b3846e49e2d68768297",
  "uncompressed_bytes": 7855013,
  "format": "gzip (mtime 0, no filename, level 9) of canonical JSON lines sorted by capsule_id"
 },
 "authority_state": "NONE: measurement only; this capsule grants and records no execution authority",
 "what_this_is": "Tool drift: for each MCP endpoint observed at two independent times, whether the tools it advertised (names; descriptions and input schemas where recorded) are the same. One capsule per endpoint in the exact-URL join of the two observations.",
 "what_this_is_not": "Not a finding of malice, poisoning or a rug-pull, and not a grade of any server. A change is a recorded difference between two observations; a version change beside it is recorded, not treated as an excuse.",
 "granularity_available": {
  "names->names": 1484,
  "names_hash->names_hash": 1
 },
 "granularity_note": "names = complete sorted tool-name lists + their sha256; per_tool_hashes adds description (raw and whitespace-collapsed) and inputSchema sha256 per tool. The 25 Sep census stored names only: description and schema drift is UNCHECKABLE for those rows.",
 "source": {
  "t1_files_sha256": {
   "/evac-bulk/census-probe-2026-09-25/results.jsonl.gz": "038a2598981e8f0e48fc03261a5a6ef44770bd0cfbc4b8aa1d6917737df67dad"
  },
  "t2_files_sha256": {
   "/evac-bulk/census-firstparty-2026-09-25/results.jsonl.gz": "ab1678d2db39999d5b390e0ac6a87f18bd242af86bb4554cdfffb1594d08c6db"
  },
  "n_t1_endpoints": 4144,
  "n_t2_endpoints": 10187,
  "n_join": 3240,
  "n_t1_only": 904,
  "n_t2_only": 6947,
  "t1_responded_absent_at_t2": 499,
  "absent_at_t2_rule": "not capsuled and never counted as REMOVED: absence from an observation is UNCHECKABLE"
 },
 "capsules_by_state": {
  "UNCHANGED_AT_NAME_GRANULARITY": 1485,
  "UNCHECKABLE": 1755
 },
 "changes_by_version_state": {},
 "private_until": "owner approves publication"
}