diff --git a/skills/todoist-cli/SKILL.md b/skills/todoist-cli/SKILL.md
index 838e3150..9730640b 100644
--- a/skills/todoist-cli/SKILL.md
+++ b/skills/todoist-cli/SKILL.md
@@ -141,6 +141,7 @@ Choosing between `task add` and `task quickadd`:
 - Use `td task add` when you need flags that Quick Add syntax can't express (`--deadline`, `--description`, `--parent`, `--duration`, `--uncompletable`, `--order`), when the text is being composed programmatically, or when you need explicit `id:` / URL references for project/section/parent.
 - `td task quickadd` supports `--stdin`, `--json`, and `--dry-run` only; everything else is embedded in the text.
 - The top-level `td add <text>` is a human shorthand for `td task quickadd` — same parser, same flag surface (`--stdin`, `--json`, `--dry-run`). Agents should prefer `td task quickadd` / `qa` for discoverability alongside the other task subcommands.
+- `--due` on `task add` / `task update` is **sent verbatim** to the API as `due_string` — the CLI does not parse or rewrite it. The server's `due_string` parser handles simple inputs ("2026-06-01", "tomorrow", "every Monday") but does **not** unpack some more complex clauses (i.e. `starting <date>`).
 
 Useful task flags:
 - `--stdin` on `task add` reads the task description from stdin; on `task quickadd` (and the top-level `td add`) it reads the full natural-language text from stdin.
diff --git a/src/commands/task/index.ts b/src/commands/task/index.ts
index d9dbea58..3402ccdc 100644
--- a/src/commands/task/index.ts
+++ b/src/commands/task/index.ts
@@ -115,7 +115,7 @@ Examples:
         .command('add [content]')
         .description('Add a task')
         .option('--content <text>', 'Task content (legacy, prefer positional argument)')
-        .option('--due <date>', 'Due date (natural language or YYYY-MM-DD)')
+        .option('--due <date>', 'Due date (YYYY-MM-DD or simple natural language; see Notes below)')
         .option('--deadline <date>', 'Deadline date (YYYY-MM-DD)')
         .addOption(
             withCaseInsensitiveChoices(
@@ -157,6 +157,14 @@ Examples:
             }
             return addTask({ ...options, content })
         })
+        .addHelpText(
+            'after',
+            `
+Notes:
+  --due is sent verbatim as the task's due_string. The server's due_string
+  parser handles simple inputs ("2026-06-01", "tomorrow", "every Monday") but
+  does not unpack some more complex clauses (i.e. "starting <date>").`,
+        )
 
     const quickaddCmd = task
         .command('quickadd [text]')
@@ -179,7 +187,10 @@ Examples:
         .command('update [ref]')
         .description('Update a task')
         .option('--content <text>', 'New content')
-        .option('--due <date>', 'New due date')
+        .option(
+            '--due <date>',
+            'New due date (YYYY-MM-DD or simple natural language; see Notes below)',
+        )
         .option('--no-due', 'Remove due date')
         .option('--deadline <date>', 'Deadline date (YYYY-MM-DD)')
         .option('--no-deadline', 'Remove deadline')
@@ -216,6 +227,14 @@ Examples:
             }
             return updateTask(ref, options)
         })
+        .addHelpText(
+            'after',
+            `
+Notes:
+  --due is sent verbatim as the task's due_string, with the same caveats as
+  "task add --due": the server's due_string parser does not unpack some more
+  complex clauses (i.e. "starting <date>").`,
+        )
 
     const moveCmd = task
         .command('move [ref]')
diff --git a/src/commands/task/task.test.ts b/src/commands/task/task.test.ts
index e3b2c181..bc89159b 100644
--- a/src/commands/task/task.test.ts
+++ b/src/commands/task/task.test.ts
@@ -2768,3 +2768,36 @@ describe('task (no args)', () => {
         stdoutSpy.mockRestore()
     })
 })
+
+describe('task add/update --due help text', () => {
+    async function captureHelp(args: string[]): Promise<string> {
+        const program = createProgram()
+        const stdoutSpy = vi.spyOn(process.stdout, 'write').mockImplementation(() => true)
+
+        await expect(program.parseAsync(['node', 'td', ...args])).rejects.toThrow()
+
+        const output = stdoutSpy.mock.calls.map((c) => String(c[0])).join('')
+        stdoutSpy.mockRestore()
+        return output
+    }
+
+    it('task add --help documents the verbatim caveat for --due', async () => {
+        const output = await captureHelp(['task', 'add', '--help'])
+
+        expect(output).toContain('--due')
+        expect(output).toContain('Notes:')
+        expect(output).toContain('sent verbatim')
+        expect(output).toContain('"starting <date>"')
+    })
+
+    it('task update --help documents the verbatim caveat and refers back to task add --due', async () => {
+        const output = await captureHelp(['task', 'update', '--help'])
+
+        expect(output).toContain('--due')
+        expect(output).toContain('Notes:')
+        expect(output).toContain('sent verbatim')
+        expect(output).toContain('"starting <date>"')
+        expect(output).toContain('same caveats as')
+        expect(output).toContain('"task add --due"')
+    })
+})
diff --git a/src/lib/skills/content.ts b/src/lib/skills/content.ts
index bc0d71da..644103da 100644
--- a/src/lib/skills/content.ts
+++ b/src/lib/skills/content.ts
@@ -137,6 +137,7 @@ Choosing between \`task add\` and \`task quickadd\`:
 - Use \`td task add\` when you need flags that Quick Add syntax can't express (\`--deadline\`, \`--description\`, \`--parent\`, \`--duration\`, \`--uncompletable\`, \`--order\`), when the text is being composed programmatically, or when you need explicit \`id:\` / URL references for project/section/parent.
 - \`td task quickadd\` supports \`--stdin\`, \`--json\`, and \`--dry-run\` only; everything else is embedded in the text.
 - The top-level \`td add <text>\` is a human shorthand for \`td task quickadd\` — same parser, same flag surface (\`--stdin\`, \`--json\`, \`--dry-run\`). Agents should prefer \`td task quickadd\` / \`qa\` for discoverability alongside the other task subcommands.
+- \`--due\` on \`task add\` / \`task update\` is **sent verbatim** to the API as \`due_string\` — the CLI does not parse or rewrite it. The server's \`due_string\` parser handles simple inputs ("2026-06-01", "tomorrow", "every Monday") but does **not** unpack some more complex clauses (i.e. \`starting <date>\`).
 
 Useful task flags:
 - \`--stdin\` on \`task add\` reads the task description from stdin; on \`task quickadd\` (and the top-level \`td add\`) it reads the full natural-language text from stdin.