diff --git a/docs/adr/0001-plugin-manifests-publish-mcp-descriptors.md b/docs/adr/0001-plugin-manifests-publish-mcp-descriptors.md
new file mode 100644
index 0000000..337aa12
--- /dev/null
+++ b/docs/adr/0001-plugin-manifests-publish-mcp-descriptors.md
@@ -0,0 +1,31 @@
+# Plugin manifests publish MCP descriptors
+
+CMS plugins expose ConnectRPC services with method-role mappings. The host can
+turn those unary methods into MCP tools, but a wasm plugin previously carried
+only its RBAC map; the host had no protobuf method descriptions or input
+schemas from which to build a safe MCP catalogue.
+
+Decision: `PluginManifest` carries repeated `MCPToolDescriptor` values at field
+38. The Go guest binding derives descriptors from linked protobuf reflection,
+includes only mapped unary methods, emits JSON object input schemas, and omits
+methods it cannot describe. The host remains responsible for validating every
+descriptor against the manifest RBAC map before registration.
+
+Generating descriptors from handwritten plugin metadata was rejected because
+it would duplicate protobuf definitions and drift from the actual service.
+Publishing every reflected method was rejected because tools without explicit
+RBAC mappings would widen the plugin's callable surface.
+
+Consequences:
+
+- Wasm plugin manifests can advertise their own ConnectRPC methods as MCP tools.
+- Descriptor capture fails closed for missing services, streaming methods, and
+  malformed or unsupported protobuf inputs.
+- Consumers must use pluginsdk v0.3.2 or newer before calling
+  `PluginManifest.GetMcpTools`.
+- `abi/proto/v1/manifest.proto` remains the language-neutral source of truth;
+  `abi/v1/manifest.pb.go` is generated output.
+
+Keywords: PluginManifest, MCPToolDescriptor, mcp_tools, GetMcpTools,
+captureMCPTools, plugin/wasmguest/mcp.go, abi/proto/v1/manifest.proto,
+abi/v1/manifest.pb.go, ConnectRPC, MCP, RBAC, pluginsdk v0.3.2
diff --git a/plugin/wasmguest/mcp_test.go b/plugin/wasmguest/mcp_test.go
index 0c8e6e3..02da35c 100644
--- a/plugin/wasmguest/mcp_test.go
+++ b/plugin/wasmguest/mcp_test.go
@@ -88,7 +88,7 @@ func registerMCPFixture(t *testing.T) {
 			}},
 		}},
 		SourceCodeInfo: &descriptorpb.SourceCodeInfo{Location: []*descriptorpb.SourceCodeInfo_Location{{
-			Path: []int32{6, 0, 2, 0}, LeadingComments: proto.String("ListArticles lists Wiki articles.\n\nSupports pagination."),
+			Path: []int32{6, 0, 2, 0}, Span: []int32{1, 0, 1, 1}, LeadingComments: proto.String("ListArticles lists Wiki articles.\n\nSupports pagination."),
 		}}},
 	}, protoregistry.GlobalFiles)
 	if err != nil {