diff --git a/.changeset/schema-preview-compositions.md b/.changeset/schema-preview-compositions.md
new file mode 100644
index 000000000..b45f05f8d
--- /dev/null
+++ b/.changeset/schema-preview-compositions.md
@@ -0,0 +1,5 @@
+---
+"executor": patch
+---
+
+Keep sibling `properties` and `required` beside an inline `allOf`, `anyOf`, or `oneOf` in TypeScript tool previews, matching what referenced definitions already did. A titled definition names the whole composition, and a composed definition whose branch refers back to it no longer falls back to `unknown`.
diff --git a/e2e/scenarios/tool-descriptions.test.ts b/e2e/scenarios/tool-descriptions.test.ts
index e646ad293..cbf3ccd66 100644
--- a/e2e/scenarios/tool-descriptions.test.ts
+++ b/e2e/scenarios/tool-descriptions.test.ts
@@ -153,6 +153,13 @@ const ordersOpenApiSpec = (baseUrl: string): string =>
                       type: "string",
                       description: "Free-form note shown to the warehouse packer.",
                     },
+                    metadata: {
+                      type: "object",
+                      description: "Extensible metadata for the order.",
+                      properties: { type: { type: "string" } },
+                      required: ["type"],
+                      allOf: [{ type: "object", additionalProperties: {} }],
+                    },
                   },
                 },
               },
@@ -488,6 +495,10 @@ scenario(
         expect(createOrder?.listDescription, "summary is the fallback description").toBe(
           "Create an order",
         );
+        expect(
+          createOrder?.inputTypeScript,
+          "sibling properties survive an inline allOf",
+        ).toContain("metadata?: ({ [k: string]: unknown; } & { type: string; })");
         expect(getOrder?.inputTypeScript, "input shape is compiled to TypeScript").toContain(
           "orderId",
         );
diff --git a/packages/core/sdk/src/schema-types.test.ts b/packages/core/sdk/src/schema-types.test.ts
index b64468e6a..77748d4e4 100644
--- a/packages/core/sdk/src/schema-types.test.ts
+++ b/packages/core/sdk/src/schema-types.test.ts
@@ -467,4 +467,81 @@ describe("schema-types", () => {
       outputTypeScript: "{ metadata: { [k: string]: unknown; }; }",
     });
   });
+
+  it.each(["allOf", "anyOf", "oneOf"])(
+    "keeps sibling properties and required keys beside an inline %s",
+    async (composition) => {
+      const siblings = {
+        properties: { type: { type: "string" }, label: { type: "string" } },
+        required: ["type"],
+        [composition]: [{ type: "object", additionalProperties: {} }],
+      };
+      const expected = {
+        type: "({ [k: string]: unknown; } & { type: string; label?: string; })",
+        definitions: {},
+      };
+      expect(await schemaToTypeScriptPreview({ type: "object", ...siblings })).toEqual(expected);
+      expect(await schemaToTypeScriptPreview(siblings)).toEqual(expected);
+    },
+  );
+
+  it("applies sibling properties per member of a nullable composed type", async () => {
+    expect(
+      await schemaToTypeScriptPreview({
+        type: ["object", "null"],
+        properties: { type: { type: "string" } },
+        required: ["type"],
+        allOf: [{ type: "object", additionalProperties: {} }],
+      }),
+    ).toEqual({
+      type: "({ [k: string]: unknown; } & ({ type: string; } | null))",
+      definitions: {},
+    });
+  });
+
+  it("names the whole composition when a titled definition has sibling properties", async () => {
+    expect(
+      await schemaToTypeScriptPreview({
+        type: "object",
+        properties: { first: { $ref: "#/$defs/Metadata" }, second: { $ref: "#/$defs/Metadata" } },
+        $defs: {
+          Metadata: {
+            title: "Metadata",
+            type: "object",
+            properties: { type: { type: "string" } },
+            required: ["type"],
+            allOf: [{ type: "object", additionalProperties: {} }],
+          },
+        },
+      }),
+    ).toEqual({
+      type: "{ first?: Metadata; second?: Metadata; }",
+      definitions: { Metadata: "({ [k: string]: unknown; } & { type: string; })" },
+    });
+  });
+
+  it("compiles a composed definition whose branch refers back to it", async () => {
+    expect(
+      await schemaToTypeScriptPreview({
+        $ref: "#/$defs/Comment",
+        $defs: {
+          Comment: {
+            type: "object",
+            properties: { body: { type: "string" } },
+            allOf: [{ $ref: "#/$defs/Base" }],
+          },
+          Base: {
+            type: "object",
+            properties: { replies: { type: "array", items: { $ref: "#/$defs/Comment" } } },
+          },
+        },
+      }),
+    ).toEqual({
+      type: "Comment",
+      definitions: {
+        Base: "{ replies?: Comment[]; }",
+        Comment: "(Base & { body?: string; })",
+      },
+    });
+  });
 });
diff --git a/packages/core/sdk/src/vendor/json-schema-to-typescript/README.md b/packages/core/sdk/src/vendor/json-schema-to-typescript/README.md
index 92881eda6..d545c176c 100644
--- a/packages/core/sdk/src/vendor/json-schema-to-typescript/README.md
+++ b/packages/core/sdk/src/vendor/json-schema-to-typescript/README.md
@@ -10,5 +10,15 @@ It also resolves only same-document JSON Pointer `$ref`s; external file and URL
 refs are rejected rather than fetched or read. It is not a public package
 surface.
 
+Sibling `properties` and `patternProperties` beside `allOf`, `anyOf`, or
+`oneOf` join the composition as one more intersection member, for inline
+schemas as well as `$id`-named ones. A definition's name belongs to the whole
+composition, and re-entering a composition through a recursive reference reuses
+its cached node. The sibling keywords intersect every branch, including
+non-object ones, so a `{ "type": "null" }` alternative beside sibling
+properties is absorbed; this matches how `$id`-named definitions already
+behaved. Keeping non-object alternatives would need per-branch kind analysis,
+which is deliberately not implemented.
+
 The upstream project is MIT licensed; the original copyright notice is included
 in `LICENCE.md`.
diff --git a/packages/core/sdk/src/vendor/json-schema-to-typescript/parser.ts b/packages/core/sdk/src/vendor/json-schema-to-typescript/parser.ts
index 0b8494096..4f80ab36c 100644
--- a/packages/core/sdk/src/vendor/json-schema-to-typescript/parser.ts
+++ b/packages/core/sdk/src/vendor/json-schema-to-typescript/parser.ts
@@ -51,6 +51,11 @@ export function parse(
   const types = normalizedSchema[Types];
 
   if (intersection) {
+    // A recursive reference can re-enter this schema while its branches are
+    // still being parsed. Reuse the cached intersection instead of appending
+    // the sibling types again or reading a placeholder's params too early.
+    const cached = processed.get(intersection)?.get("ALL_OF");
+    if (cached) return cached;
     const ast = parseAsTypeWithCache(
       intersection,
       "ALL_OF",
@@ -146,7 +151,11 @@ function parseNonLiteral(
   usedNames: UsedNames,
 ): AST {
   const definitions = getDefinitionsMemoized(getRootSchema(schema as any)); // TODO
-  const keyNameFromDefinition = findKey(definitions, (_) => _ === schema);
+  // A synthesized intersection stands for the whole definition. Its source
+  // schema now holds only the sibling constraints and must not take the name.
+  const keyNameFromDefinition = schema[Intersection]
+    ? undefined
+    : findKey(definitions, (_) => _ === schema || _[Intersection] === schema);
 
   switch (type) {
     case "ALL_OF":
diff --git a/packages/core/sdk/src/vendor/json-schema-to-typescript/typesOfSchema.ts b/packages/core/sdk/src/vendor/json-schema-to-typescript/typesOfSchema.ts
index 098b43ff7..dc3b910a4 100644
--- a/packages/core/sdk/src/vendor/json-schema-to-typescript/typesOfSchema.ts
+++ b/packages/core/sdk/src/vendor/json-schema-to-typescript/typesOfSchema.ts
@@ -141,8 +141,17 @@ const matchers: Record<SchemaType, (schema: JSONSchema) => boolean> = {
     }
     return "enum" in schema;
   },
-  UNNAMED_SCHEMA() {
-    return false; // Explicitly handled as the default case
+  UNNAMED_SCHEMA(schema) {
+    // Sibling object keywords still constrain a composed schema. `$id` schemas
+    // already join the composition through NAMED_SCHEMA; match inline ones here
+    // so the parser builds the same intersection. Type arrays are handled by
+    // UNION, which applies the object keywords to each member itself.
+    return (
+      !("$id" in schema) &&
+      (schema.type === undefined || schema.type === "object") &&
+      ("allOf" in schema || "anyOf" in schema || "oneOf" in schema) &&
+      ("properties" in schema || "patternProperties" in schema)
+    );
   },
   UNTYPED_ARRAY(schema) {
     return schema.type === "array" && !("items" in schema);