diff --git a/.changeset/fix-lexicon-fields.md b/.changeset/fix-lexicon-fields.md
new file mode 100644
index 0000000..0af1c50
--- /dev/null
+++ b/.changeset/fix-lexicon-fields.md
@@ -0,0 +1,11 @@
+---
+"@hypercerts-org/sdk-core": patch
+"@hypercerts-org/sdk-react": patch
+---
+
+fix(lexicon): correct field names and types to match lexicon schema
+
+- Fix `workTimeframeFrom/To` -> `workTimeFrameFrom/To` (capital 'F' in Frame)
+- Make `shortDescription` required for hypercert claims per lexicon schema
+- Update all interfaces, implementations, and tests to use correct field names
+- Add comprehensive lexicon documentation to README
diff --git a/packages/lexicon/package.json b/packages/lexicon/package.json
index fca65e7..1a1c8f7 100644
--- a/packages/lexicon/package.json
+++ b/packages/lexicon/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hypercerts-org/lexicon",
-  "version": "0.7.0",
+  "version": "0.8.0",
   "description": "ATProto lexicon definitions and TypeScript types for the Hypercerts protocol",
   "type": "module",
   "main": "dist/index.cjs",
diff --git a/packages/sdk-core/README.md b/packages/sdk-core/README.md
index bf49413..5febb27 100644
--- a/packages/sdk-core/README.md
+++ b/packages/sdk-core/README.md
@@ -33,11 +33,15 @@ const session = await sdk.callback(callbackParams);
 const repo = sdk.getRepository(session);
 const claim = await repo.hypercerts.create({
   title: "Tree Planting Initiative 2025",
-  description: "Planted 1000 trees in the rainforest",
-  impact: {
-    scope: ["Environmental Conservation"],
-    work: { from: "2025-01-01", to: "2025-12-31" },
-    contributors: ["did:plc:contributor1"],
+  shortDescription: "1000 trees planted in rainforest",
+  description: "Planted 1000 trees in the Amazon rainforest region",
+  workScope: "Environmental Conservation",
+  workTimeFrameFrom: "2025-01-01T00:00:00Z",
+  workTimeFrameTo: "2025-12-31T23:59:59Z",
+  rights: {
+    name: "Attribution",
+    type: "license",
+    description: "CC-BY-4.0",
   },
 });
 ```
@@ -607,21 +611,134 @@ await mockStore.set(mockSession);
 
 ### Working with Lexicons
 
+The SDK exports lexicon types and validation utilities from the `@hypercerts-org/lexicon` package for direct record manipulation and validation.
+
+#### Lexicon Types
+
+All lexicon types are available with proper TypeScript support:
+
+```typescript
+import type {
+  HypercertClaim,
+  HypercertRights,
+  HypercertContribution,
+  HypercertCollection,
+  HypercertMeasurement,
+  HypercertEvaluation,
+  HypercertLocation,
+  StrongRef,
+} from "@hypercerts-org/sdk-core";
+
+// Create a properly typed hypercert claim
+const claim: HypercertClaim = {
+  $type: "org.hypercerts.claim",
+  title: "Community Garden Project",
+  shortDescription: "Urban garden serving 50 families", // REQUIRED
+  description: "Detailed description...",
+  workScope: "Food Security",
+  workTimeFrameFrom: "2024-01-01T00:00:00Z",  // Note: Capital 'F'
+  workTimeFrameTo: "2024-12-31T00:00:00Z",    // Note: Capital 'F'
+  rights: { uri: "at://...", cid: "..." },
+  createdAt: new Date().toISOString(),
+};
+```
+
+#### Validation
+
+Validate records before creating them:
+
+```typescript
+import {
+  validate,
+  OrgHypercertsClaim,
+  HYPERCERT_COLLECTIONS,
+} from "@hypercerts-org/sdk-core";
+
+// Validate using the lexicon package
+const validation = validate(
+  HYPERCERT_COLLECTIONS.CLAIM,  // "org.hypercerts.claim"
+  claim
+);
+
+if (!validation.valid) {
+  console.error("Validation failed:", validation.error);
+}
+
+// Or use type-specific validators
+const isValid = OrgHypercertsClaim.isMain(claim);
+const validationResult = OrgHypercertsClaim.validateMain(claim);
+```
+
+#### Using LexiconRegistry
+
+For repository-level validation:
+
 ```typescript
 import {
   LexiconRegistry,
   HYPERCERT_LEXICONS,
   HYPERCERT_COLLECTIONS,
-} from "@hypercerts-org/sdk-core/lexicons";
+} from "@hypercerts-org/sdk-core";
 
 const registry = new LexiconRegistry();
 registry.registerLexicons(HYPERCERT_LEXICONS);
 
 // Validate a record
-const isValid = registry.validate(
-  "org.hypercerts.claim",
+const result = registry.validate(
+  HYPERCERT_COLLECTIONS.CLAIM,
   claimData
 );
+
+if (!result.valid) {
+  console.error("Invalid record:", result.error);
+}
+```
+
+#### Creating Records with Proper Types
+
+```typescript
+import type {
+  HypercertContribution,
+  StrongRef,
+} from "@hypercerts-org/sdk-core";
+import { HYPERCERT_COLLECTIONS } from "@hypercerts-org/sdk-core";
+
+// Create a contribution record
+const contribution: HypercertContribution = {
+  $type: HYPERCERT_COLLECTIONS.CONTRIBUTION,
+  hypercert: {
+    uri: "at://did:plc:abc/org.hypercerts.claim/xyz",
+    cid: "bafyrei...",
+  } as StrongRef,
+  contributors: ["did:plc:contributor1", "did:plc:contributor2"],
+  role: "implementer",
+  description: "On-ground implementation team",
+  workTimeframeFrom: "2024-01-01T00:00:00Z",  // Note: lowercase 'f' for contributions
+  workTimeframeTo: "2024-06-30T00:00:00Z",    // Note: lowercase 'f' for contributions
+  createdAt: new Date().toISOString(),
+};
+
+// Use with repository operations
+await repo.records.create({
+  collection: HYPERCERT_COLLECTIONS.CONTRIBUTION,
+  record: contribution,
+});
+```
+
+#### Available Lexicon Collections
+
+```typescript
+import { HYPERCERT_COLLECTIONS } from "@hypercerts-org/sdk-core";
+
+// Collection NSIDs
+HYPERCERT_COLLECTIONS.CLAIM           // "org.hypercerts.claim"
+HYPERCERT_COLLECTIONS.RIGHTS          // "org.hypercerts.claim.rights"
+HYPERCERT_COLLECTIONS.CONTRIBUTION    // "org.hypercerts.claim.contribution"
+HYPERCERT_COLLECTIONS.MEASUREMENT     // "org.hypercerts.claim.measurement"
+HYPERCERT_COLLECTIONS.EVALUATION      // "org.hypercerts.claim.evaluation"
+HYPERCERT_COLLECTIONS.EVIDENCE        // "org.hypercerts.claim.evidence"
+HYPERCERT_COLLECTIONS.COLLECTION      // "org.hypercerts.collection"
+HYPERCERT_COLLECTIONS.LOCATION        // "app.certified.location"
 ```
 
 ## Development
diff --git a/packages/sdk-core/package.json b/packages/sdk-core/package.json
index ad3ace5..8d93a68 100644
--- a/packages/sdk-core/package.json
+++ b/packages/sdk-core/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hypercerts-org/sdk-core",
-  "version": "0.7.0",
+  "version": "0.8.0",
   "description": "Framework-agnostic ATProto SDK core for authentication, repository operations, and lexicon management",
   "main": "dist/index.cjs",
   "repository": {
diff --git a/packages/sdk-core/src/repository/HypercertOperationsImpl.ts b/packages/sdk-core/src/repository/HypercertOperationsImpl.ts
index 68d8b96..eeaa3e1 100644
--- a/packages/sdk-core/src/repository/HypercertOperationsImpl.ts
+++ b/packages/sdk-core/src/repository/HypercertOperationsImpl.ts
@@ -266,18 +266,15 @@ export class HypercertOperationsImpl extends EventEmitter<HypercertEvents> imple
       const hypercertRecord: Record<string, unknown> = {
         $type: HYPERCERT_COLLECTIONS.CLAIM,
         title: params.title,
+        shortDescription: params.shortDescription,
         description: params.description,
         workScope: params.workScope,
-        workTimeframeFrom: params.workTimeframeFrom,
-        workTimeframeTo: params.workTimeframeTo,
+        workTimeFrameFrom: params.workTimeFrameFrom,
+        workTimeFrameTo: params.workTimeFrameTo,
         rights: { uri: result.rightsUri, cid: result.rightsCid },
         createdAt,
       };
 
-      if (params.shortDescription) {
-        hypercertRecord.shortDescription = params.shortDescription;
-      }
-
       if (imageBlobRef) {
         hypercertRecord.image = imageBlobRef;
       }
diff --git a/packages/sdk-core/src/repository/interfaces.ts b/packages/sdk-core/src/repository/interfaces.ts
index 4d00692..46fc274 100644
--- a/packages/sdk-core/src/repository/interfaces.ts
+++ b/packages/sdk-core/src/repository/interfaces.ts
@@ -117,14 +117,14 @@ export interface CreateHypercertParams {
    *
    * ISO 8601 date format (YYYY-MM-DD).
    */
-  workTimeframeFrom: string;
+  workTimeFrameFrom: string;
 
   /**
    * End date of the work period.
    *
    * ISO 8601 date format (YYYY-MM-DD).
    */
-  workTimeframeTo: string;
+  workTimeFrameTo: string;
 
   /**
    * Rights associated with the hypercert.
@@ -153,11 +153,11 @@ export interface CreateHypercertParams {
   };
 
   /**
-   * Optional short description for display in lists/cards.
+   * Short description for display in lists/cards.
    *
-   * Should be under 200 characters.
+   * Required field. Should be under 300 characters.
    */
-  shortDescription?: string;
+  shortDescription: string;
 
   /**
    * Optional cover image for the hypercert.
diff --git a/packages/sdk-core/tests/repository/HypercertOperationsImpl.test.ts b/packages/sdk-core/tests/repository/HypercertOperationsImpl.test.ts
index a74e2af..2d602eb 100644
--- a/packages/sdk-core/tests/repository/HypercertOperationsImpl.test.ts
+++ b/packages/sdk-core/tests/repository/HypercertOperationsImpl.test.ts
@@ -38,10 +38,11 @@ describe("HypercertOperationsImpl", () => {
   describe("create", () => {
     const validParams = {
       title: "Test Hypercert",
+      shortDescription: "A test hypercert",
       description: "A test hypercert for unit testing",
       workScope: "Testing",
-      workTimeframeFrom: "2024-01-01T00:00:00Z",
-      workTimeframeTo: "2024-12-31T23:59:59Z",
+      workTimeFrameFrom: "2024-01-01T00:00:00Z",
+      workTimeFrameTo: "2024-12-31T23:59:59Z",
       rights: {
         name: "Attribution",
         type: "CC-BY-4.0",
@@ -138,8 +139,8 @@ describe("HypercertOperationsImpl", () => {
             title: "Test",
             description: "Test",
             workScope: "Test",
-            workTimeframeFrom: "2024-01-01",
-            workTimeframeTo: "2024-12-31",
+            workTimeFrameFrom: "2024-01-01",
+            workTimeFrameTo: "2024-12-31",
             createdAt: "2024-01-01",
           },
         },
@@ -178,8 +179,8 @@ describe("HypercertOperationsImpl", () => {
             title: "Test",
             description: "Test",
             workScope: "Test",
-            workTimeframeFrom: "2024-01-01",
-            workTimeframeTo: "2024-12-31",
+            workTimeFrameFrom: "2024-01-01",
+            workTimeFrameTo: "2024-12-31",
             createdAt: "2024-01-01",
           },
         },
@@ -337,8 +338,8 @@ describe("HypercertOperationsImpl", () => {
             title: "Old Title",
             description: "Old description",
             workScope: "Old scope",
-            workTimeframeFrom: "2024-01-01",
-            workTimeframeTo: "2024-12-31",
+            workTimeFrameFrom: "2024-01-01",
+            workTimeFrameTo: "2024-12-31",
             createdAt: "2024-01-01T00:00:00Z",
             rights: { uri: "at://rights", cid: "rights-cid" },
           },
@@ -403,8 +404,8 @@ describe("HypercertOperationsImpl", () => {
             title: "Title",
             description: "Desc",
             workScope: "Scope",
-            workTimeframeFrom: "2024-01-01",
-            workTimeframeTo: "2024-12-31",
+            workTimeFrameFrom: "2024-01-01",
+            workTimeFrameTo: "2024-12-31",
             createdAt: "2024-01-01",
             rights: { uri: "at://rights", cid: "cid" },
             image: { ref: { $link: "old-image" } },
@@ -462,8 +463,8 @@ describe("HypercertOperationsImpl", () => {
             title: "Test",
             description: "Test",
             workScope: "Test",
-            workTimeframeFrom: "2024-01-01",
-            workTimeframeTo: "2024-12-31",
+            workTimeFrameFrom: "2024-01-01",
+            workTimeFrameTo: "2024-12-31",
             createdAt: "2024-01-01",
           },
         },
@@ -519,8 +520,8 @@ describe("HypercertOperationsImpl", () => {
             title: "Test",
             description: "Test",
             workScope: "Test",
-            workTimeframeFrom: "2024-01-01",
-            workTimeframeTo: "2024-12-31",
+            workTimeFrameFrom: "2024-01-01",
+            workTimeFrameTo: "2024-12-31",
             createdAt: "2024-01-01",
           },
         },
@@ -555,8 +556,8 @@ describe("HypercertOperationsImpl", () => {
             title: "Test",
             description: "Test",
             workScope: "Test",
-            workTimeframeFrom: "2024-01-01",
-            workTimeframeTo: "2024-12-31",
+            workTimeFrameFrom: "2024-01-01",
+            workTimeFrameTo: "2024-12-31",
             createdAt: "2024-01-01",
           },
         },
diff --git a/packages/sdk-react/package.json b/packages/sdk-react/package.json
index ce0c66c..852f59a 100644
--- a/packages/sdk-react/package.json
+++ b/packages/sdk-react/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hypercerts-org/sdk-react",
-  "version": "0.7.0",
+  "version": "0.8.0",
   "description": "React hooks and components for the Hypercerts ATProto SDK",
   "type": "module",
   "main": "dist/index.cjs",
diff --git a/packages/sdk-react/src/hooks/useHypercerts.ts b/packages/sdk-react/src/hooks/useHypercerts.ts
index f06e11a..f7c6c12 100644
--- a/packages/sdk-react/src/hooks/useHypercerts.ts
+++ b/packages/sdk-react/src/hooks/useHypercerts.ts
@@ -53,10 +53,11 @@ const DEFAULT_LIMIT = 50;
  *   const handleSubmit = async (data) => {
  *     const result = await create({
  *       title: data.title,
+ *       shortDescription: data.shortDesc,
  *       description: data.description,
  *       workScope: data.workScope,
- *       workTimeframeFrom: data.startDate,
- *       workTimeframeTo: data.endDate,
+ *       workTimeFrameFrom: data.startDate,
+ *       workTimeFrameTo: data.endDate,
  *       rights: {
  *         name: "CC-BY-4.0",
  *         type: "license",
diff --git a/packages/sdk-react/src/types.ts b/packages/sdk-react/src/types.ts
index 1c45f74..6548857 100644
--- a/packages/sdk-react/src/types.ts
+++ b/packages/sdk-react/src/types.ts
@@ -5,17 +5,17 @@
  */
 
 import type {
-    ATProtoSDK,
-    ATProtoSDKConfig,
-    Collaborator,
-    CollaboratorPermissions,
-    CreateHypercertParams,
-    CreateHypercertResult,
-    HypercertClaim,
-    OrganizationInfo,
-    Repository,
-    RepositoryRole,
-    Session,
+  ATProtoSDK,
+  ATProtoSDKConfig,
+  Collaborator,
+  CollaboratorPermissions,
+  CreateHypercertParams,
+  CreateHypercertResult,
+  HypercertClaim,
+  OrganizationInfo,
+  Repository,
+  RepositoryRole,
+  Session,
 } from "@hypercerts-org/sdk-core";
 import type { QueryClient } from "@tanstack/react-query";
 import type { ReactNode } from "react";
@@ -311,8 +311,8 @@ export interface UpdateHypercertParams {
   description?: string;
   workScope?: string;
   impactScope?: string;
-  workTimeframeFrom?: string;
-  workTimeframeTo?: string;
+  workTimeFrameFrom?: string;
+  workTimeFrameTo?: string;
   impactTimeframeFrom?: string;
   impactTimeframeTo?: string;
   contributors?: string[];
@@ -412,16 +412,15 @@ export interface SyncMessage {
 // ─────────────────────────────────────────────
 
 export type {
-    ATProtoSDK,
-    ATProtoSDKConfig,
-    Collaborator,
-    CollaboratorPermissions,
-    CreateHypercertParams,
-    CreateHypercertResult,
-    HypercertClaim,
-    OrganizationInfo,
-    Repository,
-    RepositoryRole,
-    Session
+  ATProtoSDK,
+  ATProtoSDKConfig,
+  Collaborator,
+  CollaboratorPermissions,
+  CreateHypercertParams,
+  CreateHypercertResult,
+  HypercertClaim,
+  OrganizationInfo,
+  Repository,
+  RepositoryRole,
+  Session,
 };
-
diff --git a/packages/sdk-react/tests/hooks/useHypercerts.test.tsx b/packages/sdk-react/tests/hooks/useHypercerts.test.tsx
index 2550c25..2bf8da3 100644
--- a/packages/sdk-react/tests/hooks/useHypercerts.test.tsx
+++ b/packages/sdk-react/tests/hooks/useHypercerts.test.tsx
@@ -218,10 +218,11 @@ describe("useHypercerts", () => {
 
       const createParams = {
         title: "New Hypercert",
-        description: "A new hypercert",
+        shortDescription: "A new hypercert",
+        description: "A new hypercert for testing",
         workScope: "Testing",
-        workTimeframeFrom: "2024-01-01",
-        workTimeframeTo: "2024-12-31",
+        workTimeFrameFrom: "2024-01-01",
+        workTimeFrameTo: "2024-12-31",
         rights: { name: "CC-BY-4.0", type: "license" as const, description: "Attribution" },
       };
 
@@ -271,10 +272,11 @@ describe("useHypercerts", () => {
       act(() => {
         result.current.create({
           title: "New HC",
+          shortDescription: "Test HC",
           description: "Test description",
           workScope: "Test",
-          workTimeframeFrom: "2024-01-01",
-          workTimeframeTo: "2024-12-31",
+          workTimeFrameFrom: "2024-01-01",
+          workTimeFrameTo: "2024-12-31",
           rights: { name: "CC-BY-4.0", type: "license" as const, description: "Attribution" },
         });
       });