Trigger: Use when the user provides document content, a file URL, or a local file path to be added to a Knowledge Base. Purpose: Add documents to a Knowledge Base. ## 📂 File Handling Rules: 1. Local Files/Paths: For local files, you MUST directly pass the absolute file path as the content. The s...
AI agents use add_kb_document to create or update resources in MemOS — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MemOS environment.
The tool creates or modifies data in a Knowledge Base in a reversible manner (documents can be removed via delete_kb_documents sibling tool). It does not execute code, delete irreversibly, move money, or merely read data.
From the tool's definition Tool description states 'Add documents to a Knowledge Base' and accepts 'document content, a file URL, or a local file path'. This is a create/modify operation that adds data to a persistent store.
Documented attack patterns abuse exactly the kind of access add_kb_document gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MemOS, and nothing reaches the server without passing your rules. This is the rule we recommend for add_kb_document:
{
"version": "1",
"default": "deny",
"tools": {
"add_kb_document": {
"limits": [
{
"counter": "add_kb_document_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_kb_document stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Trigger: Use when the user provides document content, a file URL, or a local file path to be added to a Knowledge Base. Purpose: Add documents to a Knowledge Base. ## 📂 File Handling Rules: 1. Local Files/Paths: For local files, you MUST directly pass the absolute file path as the content. The system will automatically read and process it. DO NOT convert it into Base64 yourself. You MUST provide the. It is categorised as a Write tool in the MemOS MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MemOS MCP server in PolicyLayer and add a rule for add_kb_document: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches MemOS. Nothing to install.
add_kb_document is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the add_kb_document rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for add_kb_document. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
add_kb_document is provided by the MemOS MCP server (memtensor/memos-api-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MemOS, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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10 MemOS tools catalogued and risk-classified — across an index of 43,000+ MCP servers.