diff --git a/packages/backend/src/adapters/intl/odoo.json b/packages/backend/src/adapters/intl/odoo.json
index 57b10b64..0cb3a570 100644
--- a/packages/backend/src/adapters/intl/odoo.json
+++ b/packages/backend/src/adapters/intl/odoo.json
@@ -24,7 +24,7 @@
       "X-Odoo-Database": "{{ODOO_DB}}",
       "Content-Type": "application/json"
     },
-    "healthcheckPath": "/res.users/search_count"
+    "healthcheckPath": "/../../doc-bearer/res.country.state.json"
   },
   "probe": {
     "tool": "odoo_list_partners"
@@ -134,14 +134,15 @@
           },
           "domain": {
             "type": "array",
-            "description": "Odoo domain as a list of triples.",
+            "description": "Odoo domain as a list of triples. Required by Odoo; pass [] to count every record.",
             "items": {
               "type": "array"
             }
           }
         },
         "required": [
-          "model"
+          "model",
+          "domain"
         ]
       },
       "endpointMapping": {
@@ -363,7 +364,7 @@
     },
     {
       "name": "odoo_create",
-      "description": "Create a record in any Odoo model. Writes to the live database and fires Odoo's automations — mail, stock moves and accounting entries all behave as if a person had done it.",
+      "description": "Create a record in any Odoo model and return its id (as a one-element list). Writes to the live database and fires Odoo's automations — mail, stock moves and accounting entries all behave as if a person had done it.",
       "parameters": {
         "type": "object",
         "properties": {
@@ -385,7 +386,9 @@
         "method": "POST",
         "path": "/{model}/create",
         "bodyMapping": {
-          "values": "$values"
+          "vals_list": [
+            "$values"
+          ]
         }
       }
     },
@@ -422,7 +425,7 @@
         "path": "/{model}/write",
         "bodyMapping": {
           "ids": "$ids",
-          "values": "$values"
+          "vals": "$values"
         }
       }
     },
@@ -442,14 +445,14 @@
           },
           "ids": {
             "type": "array",
-            "description": "Record ids the method operates on.",
+            "description": "Record ids the method operates on. Use [] for model-level methods such as name_search or create.",
             "items": {
               "type": "number"
             }
           },
           "kwargs": {
             "type": "object",
-            "description": "Keyword arguments for the method, when it takes any."
+            "description": "The method's keyword arguments, by name; they are sent as top-level keys of the request, which is how Odoo binds them. E.g. {\"summary\": \"Call back\", \"date_deadline\": \"2026-10-16\", \"activity_type_id\": 2} for activity_schedule on crm.lead. Omit for methods that take only the records, such as action_confirm."
           }
         },
         "required": [
@@ -463,7 +466,7 @@
         "path": "/{model}/{method}",
         "bodyMapping": {
           "ids": "$ids",
-          "kwargs": "$kwargs"
+          "__merge": "$kwargs"
         }
       }
     }
diff --git a/packages/backend/src/connectors/engines/rest.engine.spec.ts b/packages/backend/src/connectors/engines/rest.engine.spec.ts
index 65f0d567..bdcdef30 100644
--- a/packages/backend/src/connectors/engines/rest.engine.spec.ts
+++ b/packages/backend/src/connectors/engines/rest.engine.spec.ts
@@ -481,6 +481,40 @@ describe('RestEngine', () => {
     );
   });
 
+  it('spreads a __merge object into the top level of the body, explicit keys first', async () => {
+    mockedAxios.mockResolvedValue({ data: [] });
+    const mapping = {
+      method: 'POST',
+      path: '/json/2/{model}/{method}',
+      bodyMapping: { ids: '$ids', __merge: '$kwargs' },
+    };
+
+    await engine.execute(
+      { baseUrl: 'https://odoo.example.com', authType: 'NONE' },
+      mapping,
+      { model: 'crm.lead', method: 'activity_schedule', ids: [529], kwargs: { summary: 'Call', ids: [1] } },
+    );
+    expect(mockedAxios).toHaveBeenLastCalledWith(
+      expect.objectContaining({ data: { ids: [529], summary: 'Call' } }),
+    );
+
+    // Absent: nothing merged, no stray key.
+    await engine.execute(
+      { baseUrl: 'https://odoo.example.com', authType: 'NONE' },
+      mapping,
+      { model: 'sale.order', method: 'action_confirm', ids: [4] },
+    );
+    expect(mockedAxios).toHaveBeenLastCalledWith(expect.objectContaining({ data: { ids: [4] } }));
+
+    await expect(
+      engine.execute(
+        { baseUrl: 'https://odoo.example.com', authType: 'NONE' },
+        mapping,
+        { model: 'x', method: 'y', ids: [], kwargs: JSON.parse('{"__proto__": {"polluted": true}}') },
+      ),
+    ).rejects.toThrow(/prototype pollution/);
+  });
+
   it('should drop missing params from nested bodyMapping instead of sending "$TERM" literals', async () => {
     mockedAxios.mockResolvedValue({ data: {} });
 
diff --git a/packages/backend/src/connectors/engines/rest.engine.ts b/packages/backend/src/connectors/engines/rest.engine.ts
index f15453dc..b6c4940c 100644
--- a/packages/backend/src/connectors/engines/rest.engine.ts
+++ b/packages/backend/src/connectors/engines/rest.engine.ts
@@ -712,11 +712,30 @@ export class RestEngine {
     }
     const result: Record<string, unknown> = {};
     for (const [key, value] of Object.entries(mapping)) {
+      if (key === '__merge') continue;
       const resolved = this.resolveValue(value, params);
       if (resolved !== undefined) {
         result[key] = resolved;
       }
     }
+    // `__merge`: an object argument whose keys become top-level keys of the
+    // body. Some APIs take a method's arguments as the body itself (Odoo's
+    // JSON-2 `/json/2/<model>/<method>` binds every top-level key to a
+    // parameter of the method), so a generic "call a method" tool cannot know
+    // the keys in advance. Keys mapped explicitly win over merged ones.
+    if ('__merge' in mapping) {
+      const extra = this.resolveValue(mapping['__merge'], params);
+      if (extra && typeof extra === 'object' && !Array.isArray(extra)) {
+        assertNoPrototypePollution(extra);
+        // fromEntries creates own data properties only, as in safeEntries.
+        const merged = Object.fromEntries(
+          Object.entries(extra as Record<string, unknown>).filter(
+            ([key]) => !isUnsafeKey(key) && !Object.hasOwn(result, key),
+          ),
+        );
+        return { ...merged, ...result };
+      }
+    }
     return result;
   }