@@ -0,0 +1,5 @@
+---
+"@modelcontextprotocol/server-memory": patch
+---
+
+Describe the top-level array parameters of `create_entities`, `create_relations`, `add_observations` and `delete_observations` in their input schemas, so `tools/list` documents every top-level input property.
@@ -0,0 +1,68 @@
+// Asserts that every top-level input property of every memory tool carries a
+// non-empty description in tools/list (#5416). Clients and models see only the
+// property name when a description is missing, so a new tool or parameter that
+// omits one fails here rather than shipping undocumented. Driven through an SDK
+// Client over an in-memory transport, so it checks what a client receives.
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { connect, makeTempGraph } from "./helpers.js";
+import type { Connection } from "./helpers.js";
+
+describe("tool input property descriptions", () => {
+  let connection: Connection;
+  let cleanup: () => Promise<void>;
+
+  beforeEach(async () => {
+    const graph = await makeTempGraph();
+    cleanup = graph.cleanup;
+    connection = await connect(graph.filePath);
+  });
+
+  afterEach(async () => {
+    await connection.close();
+    await cleanup();
+  });
+
+  it("describes every top-level input property of every tool (#5416)", async () => {
+    const { tools } = await connection.client.listTools();
+    expect(tools.length).toBeGreaterThan(0);
+
+    const undescribed: string[] = [];
+    for (const tool of tools) {
+      for (const [name, schema] of Object.entries(
+        tool.inputSchema.properties ?? {},
+      )) {
+        const description: unknown =
+          typeof schema === "object" && schema !== null
+            ? (schema as { description?: unknown }).description
+            : undefined;
+        if (typeof description !== "string" || description.trim() === "") {
+          undescribed.push(`${tool.name}.${name}`);
+        }
+      }
+    }
+    expect(undescribed).toEqual([]);
+  });
+
+  it("describes the four top-level array parameters named in #5416", async () => {
+    const { tools } = await connection.client.listTools();
+    const descriptionOf = (tool: string, property: string): unknown => {
+      const schema = tools.find((t) => t.name === tool)?.inputSchema
+        .properties?.[property];
+      return typeof schema === "object" && schema !== null
+        ? (schema as { description?: unknown }).description
+        : undefined;
+    };
+    expect(descriptionOf("create_entities", "entities")).toBe(
+      "An array of entities to create",
+    );
+    expect(descriptionOf("create_relations", "relations")).toBe(
+      "An array of relations to create",
+    );
+    expect(descriptionOf("add_observations", "observations")).toBe(
+      "An array of entities and the observations to add to each",
+    );
+    expect(descriptionOf("delete_observations", "deletions")).toBe(
+      "An array of entities and the observations to delete from each",
+    );
+  });
+});
@@ -134,7 +134,13 @@ const expectedTools = [
       "Create multiple new entities in the knowledge graph. An entity whose name already exists, or repeats an earlier entity in the same call, is skipped and its observations are not added; the result lists the skipped names in `skipped`. Use add_observations to add observations to an existing entity.",
     inputSchema: {
       type: "object",
-      properties: { entities: { type: "array", items: entityItem(false) } },
+      properties: {
+        entities: {
+          type: "array",
+          items: entityItem(false),
+          description: "An array of entities to create",
+        },
+      },
       required: ["entities"],
       $schema: JSON_SCHEMA_2020_12,
     },
@@ -158,7 +164,13 @@ const expectedTools = [
       "Create multiple new relations between entities in the knowledge graph. Relations should be in active voice",
     inputSchema: {
       type: "object",
-      properties: { relations: { type: "array", items: relationItem(false) } },
+      properties: {
+        relations: {
+          type: "array",
+          items: relationItem(false),
+          description: "An array of relations to create",
+        },
+      },
       required: ["relations"],
       $schema: JSON_SCHEMA_2020_12,
     },
@@ -198,6 +210,8 @@ const expectedTools = [
             },
             required: ["entityName", "contents"],
           },
+          description:
+            "An array of entities and the observations to add to each",
         },
       },
       required: ["observations"],
@@ -273,6 +287,8 @@ const expectedTools = [
             },
             required: ["entityName", "observations"],
           },
+          description:
+            "An array of entities and the observations to delete from each",
         },
       },
       required: ["deletions"],
 
@@ -984,7 +984,9 @@ export function createServer(
       description:
         "Create multiple new entities in the knowledge graph. An entity whose name already exists, or repeats an earlier entity in the same call, is skipped and its observations are not added; the result lists the skipped names in `skipped`. Use add_observations to add observations to an existing entity.",
       inputSchema: z.object({
-        entities: z.array(EntitySchema),
+        entities: z
+          .array(EntitySchema)
+          .describe("An array of entities to create"),
       }),
       outputSchema: z.object({
         entities: z.array(EntitySchema),
@@ -1031,7 +1033,9 @@ export function createServer(
       description:
         "Create multiple new relations between entities in the knowledge graph. Relations should be in active voice",
       inputSchema: z.object({
-        relations: z.array(RelationSchema),
+        relations: z
+          .array(RelationSchema)
+          .describe("An array of relations to create"),
       }),
       outputSchema: z.object({
         relations: z.array(RelationSchema),
@@ -1063,16 +1067,18 @@ export function createServer(
       description:
         "Add new observations to existing entities in the knowledge graph",
       inputSchema: z.object({
-        observations: z.array(
-          z.object({
-            entityName: z
-              .string()
-              .describe("The name of the entity to add the observations to"),
-            contents: z
-              .array(z.string())
-              .describe("An array of observation contents to add"),
-          }),
-        ),
+        observations: z
+          .array(
+            z.object({
+              entityName: z
+                .string()
+                .describe("The name of the entity to add the observations to"),
+              contents: z
+                .array(z.string())
+                .describe("An array of observation contents to add"),
+            }),
+          )
+          .describe("An array of entities and the observations to add to each"),
       }),
       outputSchema: z.object({
         results: z.array(
@@ -1147,16 +1153,20 @@ export function createServer(
       description:
         "Delete specific observations from entities in the knowledge graph",
       inputSchema: z.object({
-        deletions: z.array(
-          z.object({
-            entityName: z
-              .string()
-              .describe("The name of the entity containing the observations"),
-            observations: z
-              .array(z.string())
-              .describe("An array of observations to delete"),
-          }),
-        ),
+        deletions: z
+          .array(
+            z.object({
+              entityName: z
+                .string()
+                .describe("The name of the entity containing the observations"),
+              observations: z
+                .array(z.string())
+                .describe("An array of observations to delete"),
+            }),
+          )
+          .describe(
+            "An array of entities and the observations to delete from each",
+          ),
       }),
       outputSchema: z.object({
         success: z.boolean(),
-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"@modelcontextprotocol/server-memory": patch
 +---
++
 +Describe the top-level array parameters of `create_entities`, `create_relations`, `add_observations` and `delete_observations` in their input schemas, so `tools/list` documents every top-level input property.