# kb_add

Save a fact, lesson, decision, or reference to the local persistent knowledge base.

Agent View of the PolicyLayer registry record for `kb_add`. HTML page: https://policylayer.com/tools/0x67108864-persistent-kb-mcp/kb-add

## Facts

- Tool: `kb_add`
- Server: Persistent Kb (`0x67108864/persistent-kb-mcp`) — https://policylayer.com/tools/0x67108864-persistent-kb-mcp.md
- Homepage: https://github.com/0x67108864/persistent-kb-mcp
- Risk category: Write (Medium risk)
- Registry record: grade D, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

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

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

## Why kb_add is rated Medium

This tool creates or adds new entries to a knowledge base, which is a reversible write operation. It does not execute code, delete data, move money, or trigger external operations. The blast radius is low because the operation is local, confined to a knowledge base, and reversible—entries can be modified or removed.

From the tool's own definition: "Tool name 'kb_add' and description 'Save a fact, lesson, decision, or reference to the local persistent knowledge base' indicate creation and modification of data in a SQLite database."

## Use case

AI agents use kb_add to create or update resources in Persistent Kb, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Persistent Kb environment.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Persistent Kb:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "kb_add": {
      "limits": [
        {
          "counter": "kb_add_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Persistent Kb (4)

- `kb_list` — Read — https://policylayer.com/tools/0x67108864-persistent-kb-mcp/kb-list.md
- `kb_search` — Read — https://policylayer.com/tools/0x67108864-persistent-kb-mcp/kb-search.md
- `kb_show` — Read — https://policylayer.com/tools/0x67108864-persistent-kb-mcp/kb-show.md
- `kb_tag` — Write — https://policylayer.com/tools/0x67108864-persistent-kb-mcp/kb-tag.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`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=0x67108864-persistent-kb-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/0x67108864-persistent-kb-mcp