diff --git a/packages/client/README.md b/packages/client/README.md
index ecabd1ef..ac0ebf49 100644
--- a/packages/client/README.md
+++ b/packages/client/README.md
@@ -44,6 +44,8 @@ No code changes are required — `init_client()` detects the packages at runtime
 | `LD_API_BASE_URI` | No | Evaluations management API host override; intentionally separate from `LD_BASE_URI` |
 | `LD_UI_BASE_URI` | No | LaunchDarkly application host for evaluation-run links (default: `https://app.launchdarkly.com`). Set it for a non-production project, or its runs still link to the production app |
 
+`init_client()` also sets the `launchdarkly.project_id` resource attribute to the resolved SDK key, not the project's ID.
+
 ### Run an evaluation from code (experimental)
 
 > **Experimental.** Import Evaluations from Code from `launchdarkly_ai_server.experimental.evaluations`;
diff --git a/packages/client/agents.md b/packages/client/agents.md
index 3eea9a15..06645f78 100644
--- a/packages/client/agents.md
+++ b/packages/client/agents.md
@@ -853,6 +853,7 @@ pip install "launchdarkly-ai-python[otel]"
 **Other env vars / options read by `init_client()`:**
 - `LD_SERVICE_NAME` / `options["serviceName"]` — sets `service.name` resource attribute (default: `'python-sdk'`)
 - `LD_ENVIRONMENT` / `options["environment"]` — sets `deployment.environment` resource attribute
+- Not configurable: the `launchdarkly.project_id` resource attribute is always set to the resolved SDK key, not the project's ID
 
 **Graceful degradation:** if any OTel package is missing, telemetry is silently skipped and a `logger.warning` is emitted. The LD client still initializes and all AI API calls work normally.