Add request tags documentation for spend tracking

- Add new concise doc explaining how to tag model requests
- Include Python SDK and cURL examples
- Show where tags appear in spend logs
- Add common use cases table (AWS accounts, teams, projects)
- Include how to set default tags on API keys
- Add to Spend Tracking section in sidebar

Co-authored-by: ishaan <ishaan@berri.ai>

docs/my-website/docs/proxy/request_tags.md

@@ -0,0 +1,97 @@
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+# Request Tags for Spend Tracking
+
+Add tags to your LLM requests to track spend by environment, AWS account, team, or any custom label.
+
+Tags appear in the `request_tags` field of LiteLLM spend logs, making it easy to filter and analyze costs.
+
+## Quick Start
+
+Add tags via the `metadata.tags` field in your request:
+
+<Tabs>
+<TabItem value="python" label="Python SDK">
+
+```python
+from openai import OpenAI
+
+client = OpenAI(
+    api_key="sk-1234",
+    base_url="http://0.0.0.0:4000"
+)
+
+response = client.chat.completions.create(
+    model="gpt-4",
+    messages=[{"role": "user", "content": "Hello"}],
+    extra_body={
+        "metadata": {
+            "tags": ["AWS_IAM_PROD", "us-east-1"]
+        }
+    }
+)
+```
+
+</TabItem>
+<TabItem value="curl" label="cURL">
+
+```bash
+curl -X POST 'http://0.0.0.0:4000/chat/completions' \
+  -H 'Authorization: Bearer sk-1234' \
+  -H 'Content-Type: application/json' \
+  -d '{
+    "model": "gpt-4",
+    "messages": [{"role": "user", "content": "Hello"}],
+    "metadata": {
+      "tags": ["AWS_IAM_PROD", "us-east-1"]
+    }
+  }'
+```
+
+</TabItem>
+</Tabs>
+
+## Where Tags Appear
+
+Tags are stored in the `LiteLLM_SpendLogs` table under `request_tags`:
+
+```json
+{
+  "request_id": "chatcmpl-abc123",
+  "request_tags": ["AWS_IAM_PROD", "us-east-1"],
+  "spend": 0.002,
+  "model": "gpt-4",
+  ...
+}
+```
+
+## Common Use Cases
+
+| Tag Example | Purpose |
+|-------------|---------|
+| `AWS_IAM_PROD` | Track requests from production AWS account |
+| `AWS_IAM_DEV` | Track requests from development AWS account |
+| `team-backend` | Attribute costs to backend team |
+| `project-chatbot` | Track spend for a specific project |
+
+## Set Default Tags on API Keys
+
+Set tags at the API key level so all requests automatically inherit them:
+
+```bash
+curl -X POST 'http://0.0.0.0:4000/key/generate' \
+  -H 'Authorization: Bearer sk-1234' \
+  -H 'Content-Type: application/json' \
+  -d '{
+    "metadata": {
+      "tags": ["AWS_IAM_PROD", "team-backend"]
+    }
+  }'
+```
+
+## Related
+
+- [Spend Tracking Overview](cost_tracking.md)
+- [Tag Budgets](tag_budgets.md) - Set budget limits per tag
+- [Tag Routing](tag_routing.md) - Route requests based on tags

docs/my-website/sidebars.js

@@ -442,6 +442,7 @@ const sidebars = {
           label: "Spend Tracking",
           items: [
             "proxy/cost_tracking",
+            "proxy/request_tags",
             "proxy/custom_pricing",
             "proxy/pricing_calculator",
             "proxy/provider_margins",