# list_namespaces

List all namespaces across all S3 table buckets. Permissions: You must have the s3tables:ListNamespaces permission to use this operation.

Agent View of the PolicyLayer registry record for `list_namespaces`. HTML page: https://policylayer.com/tools/aws/list-namespaces

## Facts

- Tool: `list_namespaces`
- Server: AWS (`@awslabs/mcp`) — https://policylayer.com/tools/aws.md
- Install: `npx -y @awslabs/mcp`
- Homepage: https://github.com/awslabs/mcp
- Risk category: Read (Low risk)
- Registry record: grade F, identity verified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "list_namespaces",
    "arguments": {}
  }
}
```

## Why list_namespaces is rated Low

This is a query operation that retrieves information about S3 table bucket namespaces without side effects. However, severity is medium (not low) because listing all namespaces across all S3 buckets could expose sensitive organizational structure and bucket names to an AI agent, potentially enabling reconnaissance for further attacks.

From the tool's own definition: "Tool name 'list_namespaces' and description 'List all namespaces across all S3 table buckets' indicate retrieval of data without modification. The permission requirement 's3tables:ListNamespaces' confirms read-only access to bucket metadata."

## Use case

AI agents call list_namespaces to retrieve information from AWS without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches AWS:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_namespaces": {}
  }
}
```

## Other tools on AWS (299)

- `bulk_delete_by_criteria` — Destructive — https://policylayer.com/tools/aws/bulk-delete-by-criteria.md
- `cache_delete` — Destructive — https://policylayer.com/tools/aws/cache-delete.md
- `cache_delete_many` — Destructive — https://policylayer.com/tools/aws/cache-delete-many.md
- `cache_delete_multi` — Destructive — https://policylayer.com/tools/aws/cache-delete-multi.md
- `cache_flush_all` — Destructive — https://policylayer.com/tools/aws/cache-flush-all.md
- `delete` — Destructive — https://policylayer.com/tools/aws/delete.md
- `delete_access_key` — Destructive — https://policylayer.com/tools/aws/delete-access-key.md
- `delete_datastore` — Destructive — https://policylayer.com/tools/aws/delete-datastore.md
- `delete_group` — Destructive — https://policylayer.com/tools/aws/delete-group.md
- `delete_image_set` — Destructive — https://policylayer.com/tools/aws/delete-image-set.md
- `delete_instance_in_series` — Destructive — https://policylayer.com/tools/aws/delete-instance-in-series.md
- `delete_instance_in_study` — Destructive — https://policylayer.com/tools/aws/delete-instance-in-study.md
- `delete_patient_studies` — Destructive — https://policylayer.com/tools/aws/delete-patient-studies.md
- `delete_resource` — Destructive — https://policylayer.com/tools/aws/delete-resource.md
- `delete_role_policy` — Destructive — https://policylayer.com/tools/aws/delete-role-policy.md
- `delete_series_by_uid` — Destructive — https://policylayer.com/tools/aws/delete-series-by-uid.md
- `delete_study` — Destructive — https://policylayer.com/tools/aws/delete-study.md
- `delete_user` — Destructive — https://policylayer.com/tools/aws/delete-user.md
- `delete_user_policy` — Destructive — https://policylayer.com/tools/aws/delete-user-policy.md
- `detach_user_policy` — Destructive — https://policylayer.com/tools/aws/detach-user-policy.md
- `json_arrtrim` — Destructive — https://policylayer.com/tools/aws/json-arrtrim.md
- `json_clear` — Destructive — https://policylayer.com/tools/aws/json-clear.md
- `json_del` — Destructive — https://policylayer.com/tools/aws/json-del.md
- `list_pop_left` — Destructive — https://policylayer.com/tools/aws/list-pop-left.md
- `list_trim` — Destructive — https://policylayer.com/tools/aws/list-trim.md
- `remove_instance_from_image_set` — Destructive — https://policylayer.com/tools/aws/remove-instance-from-image-set.md
- `remove_series_from_image_set` — Destructive — https://policylayer.com/tools/aws/remove-series-from-image-set.md
- `set_pop` — Destructive — https://policylayer.com/tools/aws/set-pop.md
- `sorted_set_remove_by_lex` — Destructive — https://policylayer.com/tools/aws/sorted-set-remove-by-lex.md
- `sorted_set_remove_by_score` — Destructive — https://policylayer.com/tools/aws/sorted-set-remove-by-score.md
- …and 269 more: https://policylayer.com/tools/aws.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=aws · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/aws