diff --git a/build.py b/build.py
index dc5f781..ff17494 100644
--- a/build.py
+++ b/build.py
@@ -41,6 +41,8 @@ EXCLUDE_DIRS = {"__pycache__", ".git"}
 EXCLUDE_NAMES = {".DS_Store"}
 EXCLUDE_SUFFIXES = {".pyc", ".pyo"}
 FIXED_DATE = (2026, 1, 1, 0, 0, 0)  # stable timestamp for reproducible archives
+MAX_DESCRIPTION = 500  # plugin-marketplace cap: plugin.json "description" must be UNDER this
+                       # (it has silently regressed past the limit before — fail the build now)
 
 _KEY_RE = re.compile(r'(DEFAULT_KEY\s*=\s*")([0-9a-fA-F]{16,})(")')
 
@@ -102,7 +104,14 @@ def main(argv: list[str] | None = None) -> int:
         return 1
 
     manifest_path = SRC / ".claude-plugin" / "plugin.json"
-    version = json.loads(manifest_path.read_text(encoding="utf-8"))["version"]
+    manifest = json.loads(manifest_path.read_text(encoding="utf-8"))
+    version = manifest["version"]
+    desc = manifest.get("description", "")
+    if len(desc) >= MAX_DESCRIPTION:
+        print(f"build: plugin description is {len(desc)} chars — must be under "
+              f"{MAX_DESCRIPTION} (marketplace cap). Trim \"description\" in {MANIFEST}.",
+              file=sys.stderr)
+        return 1
     files = included_files()
     arcnames = {p.relative_to(SRC).as_posix() for p in files}
     if MANIFEST not in arcnames:
diff --git a/echo-memory-1.2.0.plugin b/echo-memory-1.2.0.plugin
index 669467d..b8f9b63 100644
Binary files a/echo-memory-1.2.0.plugin and b/echo-memory-1.2.0.plugin differ
diff --git a/echo-memory.plugin b/echo-memory.plugin
index 669467d..b8f9b63 100644
Binary files a/echo-memory.plugin and b/echo-memory.plugin differ
diff --git a/echo-memory.plugin.src/.claude-plugin/plugin.json b/echo-memory.plugin.src/.claude-plugin/plugin.json
index 2d0b490..69772b1 100644
--- a/echo-memory.plugin.src/.claude-plugin/plugin.json
+++ b/echo-memory.plugin.src/.claude-plugin/plugin.json
@@ -1,7 +1,7 @@
 {
   "name": "echo-memory",
   "version": "1.2.0",
-  "description": "Persistent memory via the ECHO Obsidian vault over the Obsidian Local REST API. Cross-platform Python client (connection-pooled, with concurrent full-vault reads): one-call capture/resolve/recall/link over an entity index, hybrid BM25 + graph recall, auto-linking, an offline write-ahead queue + read cache, lock-guarded concurrency, and session-reflection capture, plus a linter-enforced routing manifest and /echo-load|save|recall|triage|health|sweep|reflect|doctor commands. Crosslinks notes across Claude/CoWork sessions.",
+  "description": "Persistent memory via the ECHO Obsidian vault over the Obsidian Local REST API. A cross-platform, connection-pooled Python client: one-call capture/resolve/recall/link over an entity index, hybrid BM25 + graph recall, auto-linking, an offline write-ahead queue, and lock-guarded concurrency. Linter-enforced routing manifest plus /echo-load|save|recall|triage|health|sweep|reflect|doctor commands. Crosslinks notes across Claude and CoWork sessions.",
   "author": {
     "name": "Jason"
   },
diff --git a/echo-memory.plugin.src/skills/echo-memory/scripts/test_echo_client.py b/echo-memory.plugin.src/skills/echo-memory/scripts/test_echo_client.py
index 5d74f1c..852146d 100644
--- a/echo-memory.plugin.src/skills/echo-memory/scripts/test_echo_client.py
+++ b/echo-memory.plugin.src/skills/echo-memory/scripts/test_echo_client.py
@@ -61,6 +61,15 @@ def test_read_many_tolerates_unreadable_file_as_none() -> None:
         echo.get_text = orig
 
 
+def test_plugin_description_under_500_chars() -> None:
+    # Marketplace cap — the description has silently regressed past it before (a 525-char
+    # relapse + an earlier "fix description length" commit). build.py fails the build on this;
+    # this guards it in CI so it's caught before packaging.
+    manifest = Path(__file__).resolve().parents[3] / ".claude-plugin" / "plugin.json"
+    desc = json.loads(manifest.read_text(encoding="utf-8")).get("description", "")
+    assert 0 < len(desc) < 500, f"plugin description is {len(desc)} chars (must be under 500)"
+
+
 def test_stem_extracts_literal_directory_prefix() -> None:
     assert check_routing.stem(r"^projects/active/[^/]+\.md$") == "projects/active/"
     assert check_routing.stem(r"^areas/(business|personal)/[^/]+\.md$") == "areas/"