diff --git a/src/tests/test_tool_metadata.py b/src/tests/test_tool_metadata.py
index 6692845..4a76785 100644
--- a/src/tests/test_tool_metadata.py
+++ b/src/tests/test_tool_metadata.py
@@ -80,6 +80,25 @@ def test_server_advertises_codealive_version_and_compact_instructions():
     assert "DISCOVER → SEARCH → READ → EXPAND" in mcp.instructions
     assert "chat only when the user explicitly requests" in mcp.instructions.lower()
 
+@pytest.mark.asyncio
+async def test_relationships_description_states_the_call_site_contract():
+    """The three call-site rules are only enforceable through the tool description: the backend can
+    omit positions for a repository indexed before call sites shipped, and a model that reads a
+    missing position as "no call" draws the opposite conclusion from the truth."""
+    # Arrange / Act
+    async with Client(mcp) as client:
+        tools = await client.list_tools()
+
+    # Assert
+    description = {tool.name: tool for tool in tools}["get_artifact_relationships"].description
+    assert description is not None
+    assert "call_sites" in description
+    assert "call_site_count" in description
+    # Missing position means "not indexed yet", never "no call".
+    assert "never" in description.lower()
+    # No parameter enables them, so the model must not go hunting for one.
+    assert "no parameter" in description.lower()
+
 
 def test_imported_server_selects_single_span_ownership_without_main():
     import os
diff --git a/src/tools/artifact_relationships.py b/src/tools/artifact_relationships.py
index 545a2db..8327c76 100644
--- a/src/tools/artifact_relationships.py
+++ b/src/tools/artifact_relationships.py
@@ -33,6 +33,17 @@ async def get_artifact_relationships(
     This is a graph expansion tool, not a search tool. Use identifiers returned
     by semantic_search, grep_search, fetch_artifacts, read_file, or prior
     relationship results.
+
+    Call relationships also carry `call_sites` — each one a `position` written as
+    `path:line`, where the call is actually written — plus `call_site_count` for
+    how many exist in total. Read those exact lines instead of fetching the whole
+    caller. There is no parameter for this: positions come back whenever they are
+    known, so do not look for a flag. A call item with no `call_sites` means the position is not
+    indexed yet (the repository was indexed before call sites shipped, or that one
+    edge could not be located); it never means the call does not happen — the item
+    being listed at all is what says the call exists. A `confidence` on a site
+    appears only when the position is approximate; its absence means exact. For
+    incoming calls the file shown is the caller's file, not this artifact's.
     """
     tool_name = "get_artifact_relationships"
     require_text(identifier, tool_name, "identifier")
diff --git a/uv.lock b/uv.lock
index 4f12639..70b136b 100644
--- a/uv.lock
+++ b/uv.lock
@@ -48,15 +48,15 @@ wheels = [
 
 [[package]]
 name = "anyio"
-version = "4.14.1"
+version = "4.15.1"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "idna" },
-    { name = "typing-extensions", marker = "python_full_version < '3.13'" },
+    { name = "typing-extensions", marker = "python_full_version < '3.15'" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/3b/72/5562aabb8dd7181e8e860622a38bea08d17842b99ecd4c91f84ac95251b0/anyio-4.14.1.tar.gz", hash = "sha256:8d648a3544c1a700e3ff78615cd679e4c5c3f149904287e73687b2596963629e", size = 254831, upload-time = "2026-06-24T20:56:06.017Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/a9/d2/f4d173e22df740bc37b1db102b386ba719b66e95b0f0d751f556b387e6d2/anyio-4.15.1.tar.gz", hash = "sha256:9f28306018cbd6d329e64a36d58256edff76dd996fe423bc957326e578b82a94", size = 276966, upload-time = "2026-09-05T10:42:39.44Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/b0/7b/90df4a0a816d98d6ea26f559d87836d494a2cf1fcf063be67df50a7bcc30/anyio-4.14.1-py3-none-any.whl", hash = "sha256:4e5533c5b8ff0a24f5d7a176cbe6877129cd183893f66b537f8f227d10527d72", size = 124875, upload-time = "2026-06-24T20:56:04.413Z" },
+    { url = "https://files.pythonhosted.org/packages/12/b8/4bd346e22b28902df4d651910f5242c28d84e4a5c2435ca5c3f797ed7e2e/anyio-4.15.1-py3-none-any.whl", hash = "sha256:6152fdbbf9a77fdec97731721bebf7c4c44f7c29b424b0065826173efc7ed101", size = 132079, upload-time = "2026-09-05T10:42:37.923Z" },
 ]
 
 [[package]]