diff --git a/communique.toml b/communique.toml
index ee652a75..903d397c 100644
--- a/communique.toml
+++ b/communique.toml
@@ -17,7 +17,12 @@ maintainers validating GitHub Release and npm artifacts.
 
 [defaults]
 #model = "claude-opus-4-7"
-#max_tokens = 4096
+# Communique 1.1.3 caps each model response at 4096 tokens when this is unset.
+# One submit_release_notes call (changelog + title + body) needs more than that
+# once a release has ~15 commits, so every call was cut off mid-answer and Release
+# Please failed with communique::malformed_submission. 16384 is the default that
+# Communique 1.2.2 moved to.
+max_tokens = 16384
 repo = "coder/agent-tty"
 #provider = "anthropic"
 #base_url = ""
diff --git a/docs/RELEASE-PROCESS.md b/docs/RELEASE-PROCESS.md
index 9516af62..91a5fdd8 100644
--- a/docs/RELEASE-PROCESS.md
+++ b/docs/RELEASE-PROCESS.md
@@ -243,6 +243,12 @@ gh workflow run release-please.yml
 
 Wrong version → land a `Release-As` commit. Wrong notes → fix the merged feature PR bodies (or add `BEGIN_COMMIT_OVERRIDE` blocks) and rerun. Never edit the release PR directly; edits are overwritten.
 
+### Release Please fails with `communique::malformed_submission`
+
+Communique gave up after three `submit_release_notes` calls that lacked a required field (`changelog`, `release_title` or `release_body`). The cause seen so far is the model answer being cut off at Communique's response limit, `max_tokens`. Communique 1.1.3 uses 4096 when `communique.toml` does not set it, and one call needs more than that once a release has about 15 commits. `communique.toml` therefore sets `max_tokens = 16384` under `[defaults]`. A key outside `[defaults]` is silently ignored.
+
+A run log that shows `WARN submit_release_notes was malformed 3 times ... salvaging the last attempt` hit the same cut-off and only passed because the last attempt kept its changelog. If the error returns, raise `max_tokens` before rerunning.
+
 ### The release PR merged but no tag or GitHub Release appeared
 
 The Release Please run triggered by the merge failed before `createReleases()` finished. Rerun it — release creation is idempotent (it finds merged release PRs still labeled `autorelease: pending`):
diff --git a/src/tools/README.md b/src/tools/README.md
index 907a0a41..7aa62242 100644
--- a/src/tools/README.md
+++ b/src/tools/README.md
@@ -24,7 +24,7 @@ Maintainer tools that run with `tsx` outside the `agent-tty` CLI. They build and
 - `applyHeroVideoUrls(options)`: subcommand `apply-video-urls --codex-url URL --claude-url URL [--bundle-dir] [--root-readme]`. Writes the uploaded video URLs into the root `README.md` and the bundle `README.md`. [hero-video-playback.ts:applyHeroVideoUrls]
 - `posterConcatFilter`, `replaceVideoSrcs`, `PrepareHeroVideoUploadAssetsOptions`, `ApplyHeroVideoUrlsOptions`: ffmpeg filter and `<video src>` rewrite helpers. [hero-video-playback.ts:posterConcatFilter] [hero-video-playback.ts:replaceVideoSrcs]
 - `main` in `release-please-runner.ts` (flag `--dry-run`): runs release-please as a library with the `CommuniqueNodeStrategy` release type and Communique changelog notes. [release-please-runner.ts:main] [release-please-runner.ts:CommuniqueNodeStrategy] [release-please-runner.ts:createCommuniqueChangelogNotes]
-- `UnreleasedAwareChangelog`, `formatChangelogSection`, `normalizeCommuniqueBody`, `buildCommuniqueArgs`, `assertLlmCredentials`, `formatReleaseOutputs`, `formatPullRequestOutputs`, `todayIsoDate`, and the types `CommuniqueInvocation`, `CommuniqueRunner`, `RunnerOutputs`: changelog and workflow-output helpers. [release-please-runner.ts:UnreleasedAwareChangelog] [release-please-runner.ts:formatChangelogSection] [release-please-runner.ts:RunnerOutputs]
+- `UnreleasedAwareChangelog`, `formatChangelogSection`, `normalizeCommuniqueBody`, `buildCommuniqueArgs`, `describeCommuniqueFailure`, `assertLlmCredentials`, `formatReleaseOutputs`, `formatPullRequestOutputs`, `todayIsoDate`, and the types `CommuniqueInvocation`, `CommuniqueRunner`, `RunnerOutputs`: changelog and workflow-output helpers. [release-please-runner.ts:UnreleasedAwareChangelog] [release-please-runner.ts:formatChangelogSection] [release-please-runner.ts:RunnerOutputs] [release-please-runner.ts:describeCommuniqueFailure]
 
 ## Invariants
 
@@ -39,6 +39,7 @@ Maintainer tools that run with `tsx` outside the `agent-tty` CLI. They build and
 - Promotion validates the manifest with `CanonicalBundleManifestSchema.parse` through `writeCanonicalBundleManifest`. It throws `leak check failed` when `buildLeakFindings` finds account-sensitive patterns in the promoted text files: home paths, emails, the `ANTHROPIC_AUTH_TOKEN`, `ANTHROPIC_API_KEY` and `OPENAI_API_KEY` names, `API Usage Billing`, `Auth conflict` and `Welcome back` lines, and token-like strings. The check runs on the sanitized texts before promotion clears or writes `--bundle-dir`, so a failure leaves the bundle unchanged. [hero-demo.ts:promote] [hero-demo.ts:buildLeakFindings]
 - `applyHeroVideoUrls` asserts that each URL starts with `https://github.com/user-attachments/assets/` and that exactly two `<video src>` tags match. [hero-video-playback.ts:applyHeroVideoUrls] [hero-video-playback.ts:replaceVideoSrcs]
 - `assertLlmCredentials` requires `ANTHROPIC_API_KEY` or `OPENAI_API_KEY`, plus `COMMUNIQUE_MODEL` when only the OpenAI key is set. `main` requires `GITHUB_TOKEN` and `GITHUB_REPOSITORY` through `requireEnv`. [release-please-runner.ts:assertLlmCredentials] [release-please-runner.ts:requireEnv]
+- `describeCommuniqueFailure` appends a hint that names `max_tokens` when Communique reports `communique::malformed_submission`. `communique.toml` sets `[defaults].max_tokens = 16384` because Communique 1.1.3 cuts each response at 4096 tokens otherwise. [release-please-runner.ts:describeCommuniqueFailure]
 - A comment on `formatChangelogSection` states that the heading must not contain a `v` after `[`, because release-please then cannot parse the merged PR. [release-please-runner.ts:formatChangelogSection]
 
 ## Side Effects
diff --git a/src/tools/release-please-runner.ts b/src/tools/release-please-runner.ts
index 5368dbd4..98eb6491 100644
--- a/src/tools/release-please-runner.ts
+++ b/src/tools/release-please-runner.ts
@@ -177,6 +177,26 @@ export type CommuniqueRunner = (
   env: NodeJS.ProcessEnv,
 ) => Promise<void>;
 
+const MALFORMED_SUBMISSION_HINT =
+  'hint: communique::malformed_submission usually means the model answer was cut ' +
+  'off at the response token ceiling before it wrote every required field. ' +
+  'Raise `max_tokens` under [defaults] in communique.toml (Communique 1.1.3 ' +
+  'uses 4096 when it is unset).';
+
+/**
+ * Error text for a failed `communique` run: the command line and its stderr,
+ * plus a hint for the one failure whose message does not name its cause.
+ */
+export function describeCommuniqueFailure(
+  args: readonly string[],
+  stderr: string,
+): string {
+  const message = `communique ${args.join(' ')} failed${stderr === '' ? '' : `:\n${stderr}`}`;
+  return stderr.includes('communique::malformed_submission')
+    ? `${message}\n${MALFORMED_SUBMISSION_HINT}`
+    : message;
+}
+
 async function runCommuniqueBinary(
   args: string[],
   env: NodeJS.ProcessEnv,
@@ -194,10 +214,7 @@ async function runCommuniqueBinary(
       error instanceof Object && 'stderr' in error
         ? String((error as { stderr: unknown }).stderr)
         : '';
-    throw new Error(
-      `communique ${args.join(' ')} failed${stderr === '' ? '' : `:\n${stderr}`}`,
-      { cause: error },
-    );
+    throw new Error(describeCommuniqueFailure(args, stderr), { cause: error });
   }
 }
 
diff --git a/test/unit/tools/release-please-runner.test.ts b/test/unit/tools/release-please-runner.test.ts
index 338110b1..31fb4620 100644
--- a/test/unit/tools/release-please-runner.test.ts
+++ b/test/unit/tools/release-please-runner.test.ts
@@ -19,6 +19,7 @@ import {
   assertLlmCredentials,
   buildCommuniqueArgs,
   createCommuniqueChangelogNotes,
+  describeCommuniqueFailure,
   formatChangelogSection,
   formatPullRequestOutputs,
   formatReleaseOutputs,
@@ -391,6 +392,56 @@ describe('createCommuniqueChangelogNotes', () => {
   });
 });
 
+describe('describeCommuniqueFailure', () => {
+  const args = ['generate', 'HEAD', 'v0.5.0', '--concise'];
+
+  it('points a malformed submission at the max_tokens ceiling', () => {
+    const stderr = [
+      'Error: communique::malformed_submission',
+      '  × submit_release_notes was malformed 3 times',
+    ].join('\n');
+
+    const message = describeCommuniqueFailure(args, stderr);
+
+    expect(message).toContain(
+      `communique ${args.join(' ')} failed:\n${stderr}`,
+    );
+    expect(message).toContain('max_tokens');
+    expect(message).toContain('communique.toml');
+  });
+
+  it('adds no hint to other failures', () => {
+    expect(
+      describeCommuniqueFailure(args, 'Error: ANTHROPIC_API_KEY not set'),
+    ).toBe(
+      `communique ${args.join(' ')} failed:\nError: ANTHROPIC_API_KEY not set`,
+    );
+    expect(describeCommuniqueFailure(args, '')).toBe(
+      `communique ${args.join(' ')} failed`,
+    );
+  });
+});
+
+describe('communique.toml', () => {
+  // Communique 1.1.3 sends 4096 as the response ceiling when this key is
+  // missing, and cuts every submit_release_notes call off at that size once a
+  // release has ~15 commits (Release Please then fails with
+  // communique::malformed_submission). A key outside [defaults] is ignored
+  // silently, so check the section too.
+  it('sets a response ceiling above the communique 1.1.3 default in [defaults]', () => {
+    const toml = readFileSync(
+      new URL('../../../communique.toml', import.meta.url),
+      'utf8',
+    );
+    const defaults = toml.split(/^\[defaults\]\s*$/m)[1];
+    expect(defaults).toBeDefined();
+    const section = (defaults ?? '').split(/^\[/m)[0] ?? '';
+    const match = /^max_tokens\s*=\s*(\d+)\s*$/m.exec(section);
+    expect(match).not.toBeNull();
+    expect(Number(match?.[1])).toBeGreaterThanOrEqual(16384);
+  });
+});
+
 describe('CommuniqueNodeStrategy branch component', () => {
   // The branch component follows include-component-in-tag (the stock strategy
   // always embeds the package name in the branch). The fake `this` works