chore: remove override value print, add erroring when disabled, cleanup

Author: gagik

src/common/config/configOverrides.ts

@@ -27,7 +27,7 @@ export function applyConfigOverrides({
 
     // Only apply overrides if allowRequestOverrides is enabled
     if (!baseConfig.allowRequestOverrides) {
-        return baseConfig;
+        throw new Error("Request overrides are not enabled");
     }
 
     const result: UserConfig = { ...baseConfig };
@@ -69,11 +69,6 @@ function extractConfigOverrides(
         }
         assertValidConfigKey(configKey);
 
-        const behavior = getConfigMeta(configKey)?.overrideBehavior || "not-allowed";
-        if (behavior === "not-allowed") {
-            throw new Error(`Config key ${configKey} is not allowed to be overridden`);
-        }
-
         const parsedValue = parseConfigValue(configKey, value);
         if (parsedValue !== undefined) {
             overrides[configKey] = parsedValue;
@@ -143,7 +138,7 @@ function applyOverride(
             return behavior(baseValue, overrideValue);
         } catch (error) {
             throw new Error(
-                `Cannot apply override for ${key} from ${JSON.stringify(baseValue)} to ${JSON.stringify(overrideValue)}: ${error instanceof Error ? error.message : String(error)}`
+                `Cannot apply override for ${key}: ${error instanceof Error ? error.message : String(error)}`
             );
         }
     }
@@ -155,9 +150,10 @@ function applyOverride(
             if (Array.isArray(baseValue) && Array.isArray(overrideValue)) {
                 return [...(baseValue as unknown[]), ...(overrideValue as unknown[])];
             }
-            throw new Error("Cannot merge non-array values, did you mean to use the 'override' behavior?");
+            throw new Error(`Cannot merge non-array values for ${key}`);
 
         case "not-allowed":
+            throw new Error(`Config key ${key} is not allowed to be overridden`);
         default:
             return baseValue;
     }

tests/integration/transports/configOverrides.test.ts

@@ -48,26 +48,25 @@ describe("Config Overrides via HTTP", () => {
     });
 
     describe("override behavior", () => {
-        it("should not apply overrides when allowRequestOverrides is false", async () => {
+        it("should error when allowRequestOverrides is false", async () => {
             await startRunner({
                 ...defaultTestConfig,
                 httpPort: 0,
                 readOnly: false,
                 allowRequestOverrides: false,
             });
 
-            await connectClient({
-                ["x-mongodb-mcp-read-only"]: "true",
-            });
-
-            const response = await client.listTools();
-
-            expect(response).toBeDefined();
-            expect(response.tools).toBeDefined();
-
-            // Verify read-only mode is NOT applied - insert-many should still be available
-            const writeTools = response.tools.filter((tool) => tool.name === "insert-many");
-            expect(writeTools.length).toBe(1);
+            try {
+                await connectClient({
+                    ["x-mongodb-mcp-read-only"]: "true",
+                });
+                expect.fail("Expected an error to be thrown");
+            } catch (error) {
+                if (!(error instanceof Error)) {
+                    throw new Error("Expected an error to be thrown");
+                }
+                expect(error.message).toContain("Request overrides are not enabled");
+            }
         });
 
         it("should override readOnly config via header (false to true)", async () => {
@@ -376,9 +375,7 @@ describe("Config Overrides via HTTP", () => {
                     throw new Error("Expected an error to be thrown");
                 }
                 expect(error.message).toContain("Error POSTing to endpoint (HTTP 400)");
-                expect(error.message).toContain(
-                    `Cannot apply override for readOnly from true to false: Can only set to true`
-                );
+                expect(error.message).toContain(`Cannot apply override for readOnly: Can only set to true`);
             }
         });
     });

tests/unit/common/config/configOverrides.test.ts

@@ -80,10 +80,9 @@ describe("configOverrides", () => {
                     ...baseConfig,
                     allowRequestOverrides: false,
                 } as UserConfig;
-                const result = applyConfigOverrides({ baseConfig: configWithOverridesDisabled, request });
-                // Config should remain unchanged
-                expect(result.readOnly).toBe(false);
-                expect(result.idleTimeoutMs).toBe(600_000);
+                expect(() => applyConfigOverrides({ baseConfig: configWithOverridesDisabled, request })).to.throw(
+                    "Request overrides are not enabled"
+                );
             });
 
             it("should apply overrides when allowRequestOverrides is true", () => {
@@ -107,9 +106,9 @@ describe("configOverrides", () => {
                 };
                 // eslint-disable-next-line @typescript-eslint/no-unused-vars
                 const { allowRequestOverrides, ...configWithoutOverridesFlag } = baseConfig;
-                const result = applyConfigOverrides({ baseConfig: configWithoutOverridesFlag as UserConfig, request });
-                // Should not apply overrides since the default is false
-                expect(result.readOnly).toBe(false);
+                expect(() =>
+                    applyConfigOverrides({ baseConfig: configWithoutOverridesFlag as UserConfig, request })
+                ).to.throw("Request overrides are not enabled");
             });
         });
 
@@ -254,7 +253,7 @@ describe("configOverrides", () => {
                 const request: RequestContext = { headers: { "x-mongodb-mcp-read-only": "false" } };
                 expect(() =>
                     applyConfigOverrides({ baseConfig: { ...baseConfig, readOnly: true } as UserConfig, request })
-                ).toThrow("Cannot apply override for readOnly from true to false: Can only set to true");
+                ).toThrow("Cannot apply override for readOnly: Can only set to true");
             });
 
             it("should allow indexCheck override from false to true", () => {
@@ -270,7 +269,7 @@ describe("configOverrides", () => {
                 const request: RequestContext = { headers: { "x-mongodb-mcp-index-check": "false" } };
                 expect(() =>
                     applyConfigOverrides({ baseConfig: { ...baseConfig, indexCheck: true } as UserConfig, request })
-                ).toThrow("Cannot apply override for indexCheck from true to false: Can only set to true");
+                ).toThrow("Cannot apply override for indexCheck: Can only set to true");
             });
 
             it("should allow disableEmbeddingsValidation override from true to false", () => {
@@ -289,9 +288,7 @@ describe("configOverrides", () => {
                         baseConfig: { ...baseConfig, disableEmbeddingsValidation: false } as UserConfig,
                         request,
                     })
-                ).toThrow(
-                    "Cannot apply override for disableEmbeddingsValidation from false to true: Can only set to false"
-                );
+                ).toThrow("Cannot apply override for disableEmbeddingsValidation: Can only set to false");
             });
         });