diff --git a/AGENTS.md b/AGENTS.md
index b944fb4..d66a228 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -24,7 +24,8 @@ AI assistant multiplexer that connects messaging channels to coding agents via
   connects the `nq` job to its message directory.
 - **Agents:** Supported agents are `pi` and `claude`, configurable via
   `~/.config/muxclaw/config.json`. Default agent is `pi`. Real-time response
-  streaming is supported for both.
+  streaming is supported for both. For `claude`, `muxclaw` automatically passes
+  `--add-dir` to allow access to the message attachments directory.
 
 ## Code Style & Conventions
 
diff --git a/cli.ts b/cli.ts
index e26c519..93532a7 100644
--- a/cli.ts
+++ b/cli.ts
@@ -243,13 +243,15 @@ function getAgentCommand({
 		case 'claude': {
 			const args = stream
 				? [
+					'--add-dir',
+					DATA_DIR,
 					'--output-format',
 					'stream-json',
 					'--verbose',
 					'--include-partial-messages',
 					'-p',
 				]
-				: ['-p'];
+				: ['--add-dir', DATA_DIR, '-p'];
 			return { cmd: 'claude', args };
 		}
 		case 'pi': {
diff --git a/cli_test.ts b/cli_test.ts
index f66f729..7afff4d 100644
--- a/cli_test.ts
+++ b/cli_test.ts
@@ -535,6 +535,8 @@ describe('dispatch', () => {
 		assertSpyCall(cmdStub, 0, {
 			args: ['claude', {
 				args: [
+					'--add-dir',
+					DATA_DIR,
 					'--output-format',
 					'stream-json',
 					'--verbose',