diff --git a/.changeset/lean-connection-health.md b/.changeset/lean-connection-health.md
new file mode 100644
index 000000000..02577c496
--- /dev/null
+++ b/.changeset/lean-connection-health.md
@@ -0,0 +1,5 @@
+---
+"@executor-js/sdk": patch
+---
+
+Keep `connections.list` health output compact unless callers opt into diagnostics with `verbose: true`. Default list responses now retain only the health status, identity, and check timestamp; verbose responses continue to include HTTP status, diagnostic detail, and bounded upstream response samples.
diff --git a/packages/core/sdk/src/connections.test.ts b/packages/core/sdk/src/connections.test.ts
index 7ed046f65..937aae3ba 100644
--- a/packages/core/sdk/src/connections.test.ts
+++ b/packages/core/sdk/src/connections.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from "@effect/vitest";
-import { Effect, Predicate, Result } from "effect";
+import { Effect, Predicate, Result, Schema } from "effect";
 
 import {
   AuthTemplateSlug,
@@ -11,6 +11,7 @@ import {
   ToolName,
 } from "./ids";
 import { createExecutor } from "./executor";
+import { HealthCheckResult } from "./health-check";
 import { definePlugin } from "./plugin";
 import type { CredentialProvider } from "./provider";
 import { makeTestConfig, makeTestExecutor } from "./testing";
@@ -43,6 +44,11 @@ const memoryProvider = (): CredentialProvider => {
 const INTEG = IntegrationSlug.make("vercel");
 const TEMPLATE = AuthTemplateSlug.make("apiKey");
 
+const ConnectionListHealthOutput = Schema.Struct({
+  connections: Schema.Array(Schema.Struct({ lastHealth: Schema.NullOr(HealthCheckResult) })),
+});
+const decodeConnectionListHealthOutput = Schema.decodeUnknownEffect(ConnectionListHealthOutput);
+
 const demoPlugin = definePlugin(() => ({
   id: "demo" as const,
   credentialProviders: [memoryProvider()],
@@ -263,6 +269,58 @@ describe("connections.create", () => {
 });
 
 describe("connections.list / get", () => {
+  it.effect("only includes full health diagnostics in verbose core tool output", () =>
+    Effect.gen(function* () {
+      const config = makeTestConfig({ plugins: [demoPlugin] as const, coreTools: {} });
+      const executor = yield* createExecutor(config);
+      yield* executor.demo.seed();
+      yield* executor.connections.create({
+        owner: "org",
+        name: ConnectionName.make("health"),
+        integration: INTEG,
+        template: TEMPLATE,
+        value: "v",
+      });
+
+      const health = {
+        status: "healthy" as const,
+        identity: "account@example.com",
+        checkedAt: 1234,
+        httpStatus: 200,
+        detail: "GET /me returned 200",
+        responseSample: [{ path: "user.email", value: "account@example.com" }],
+      };
+      yield* Effect.promise(() =>
+        config.db.updateMany("connection", {
+          where: (b) => b.and(b("integration", "=", String(INTEG)), b("name", "=", "health")),
+          set: { last_health: health },
+        }),
+      );
+
+      const list = (input: { readonly verbose?: boolean }) =>
+        executor
+          .execute(ToolAddress.make("executor.coreTools.connections.list"), {
+            integration: String(INTEG),
+            owner: "org",
+            ...input,
+          })
+          .pipe(Effect.flatMap(decodeConnectionListHealthOutput));
+
+      const defaultList = yield* list({});
+      const nonVerboseList = yield* list({ verbose: false });
+      const verboseList = yield* list({ verbose: true });
+      const summary = {
+        status: "healthy",
+        identity: "account@example.com",
+        checkedAt: 1234,
+      };
+
+      expect(defaultList.connections[0]?.lastHealth).toEqual(summary);
+      expect(nonVerboseList.connections[0]?.lastHealth).toEqual(summary);
+      expect(verboseList.connections[0]?.lastHealth).toEqual(health);
+    }),
+  );
+
   it.effect("lists created connections and filters by integration", () =>
     Effect.gen(function* () {
       const executor = yield* setup();
diff --git a/packages/core/sdk/src/core-tools.ts b/packages/core/sdk/src/core-tools.ts
index e6dc78ce7..e78da61f3 100644
--- a/packages/core/sdk/src/core-tools.ts
+++ b/packages/core/sdk/src/core-tools.ts
@@ -88,10 +88,10 @@ const ConnectionsListInput = Schema.Struct({
   verbose: Schema.optional(Schema.Boolean),
 });
 
-/** Lean per-connection shape for list scans. Omits the full `oauthScope`
- *  grant string (a single connection's scope list can run to thousands of
- *  characters and dominates the payload) in favor of `oauthScopeCount`. The
- *  full scope is included only when the caller passes `verbose: true`. */
+/** Lean per-connection shape for list scans. The default projection summarizes
+ *  the full `oauthScope` grant string as `oauthScopeCount` and trims health
+ *  probe diagnostics. Those optional fields are populated only for `verbose:
+ *  true`. */
 const ConnectionListItem = Schema.Struct({
   owner: OwnerSchema,
   name: Schema.String,
@@ -389,8 +389,8 @@ const connectionToOutput = (connection: Connection) => ({
 const oauthScopeCount = (scope: string | null | undefined): number | null =>
   scope == null ? null : scope.split(/\s+/).filter(Boolean).length;
 
-/** Lean projection for `connections.list`. Summarizes `oauthScope` to a count
- *  unless `verbose`, where the full grant string is included too. */
+/** Lean projection for `connections.list`. Summarizes `oauthScope` and health
+ * diagnostics unless `verbose`, where the full grant string is included too. */
 const connectionToListItem = (connection: Connection, verbose: boolean) => ({
   owner: connection.owner,
   name: String(connection.name),
@@ -404,7 +404,17 @@ const connectionToListItem = (connection: Connection, verbose: boolean) => ({
   oauthClient: connection.oauthClient == null ? null : String(connection.oauthClient),
   oauthClientOwner: connection.oauthClientOwner ?? null,
   oauthScopeCount: oauthScopeCount(connection.oauthScope),
-  lastHealth: connection.lastHealth ?? null,
+  // Keep full probe diagnostics behind the explicit verbose opt-in.
+  lastHealth:
+    connection.lastHealth == null || verbose
+      ? (connection.lastHealth ?? null)
+      : {
+          status: connection.lastHealth.status,
+          ...(connection.lastHealth.identity !== undefined
+            ? { identity: connection.lastHealth.identity }
+            : {}),
+          checkedAt: connection.lastHealth.checkedAt,
+        },
   ...(verbose ? { oauthScope: connection.oauthScope ?? null } : {}),
 });
 
diff --git a/packages/core/sdk/src/executor.test.ts b/packages/core/sdk/src/executor.test.ts
index 029b06d75..00b878fd6 100644
--- a/packages/core/sdk/src/executor.test.ts
+++ b/packages/core/sdk/src/executor.test.ts
@@ -438,7 +438,7 @@ describe("createExecutor", () => {
 
       const listed = yield* executor.execute(
         ToolAddress.make("executor.coreTools.connections.list"),
-        { integration: "diagnostics" },
+        { integration: "diagnostics", verbose: true },
       );
       expect(listed).toMatchObject({
         connections: [