AI agents use update_knowledge to create or update resources in Opencode Personal Knowledge — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Opencode Personal Knowledge environment.
This tool modifies existing knowledge entries in the vector database reversibly. Updates can be undone by updating again or reverting to previous values, so it does not qualify as Destructive. It is a Write operation with medium severity because misuse could corrupt personal knowledge data, but the effect is reversible and scoped to a local knowledge base rather than critical systems or financial resources.
From the tool's definition Tool name 'update_knowledge' and description 'Update an existing knowledge entry' indicate modification of existing data.
Documented attack patterns abuse exactly the kind of access update_knowledge gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Opencode Personal Knowledge, and nothing reaches the server without passing your rules. This is the rule we recommend for update_knowledge:
{
"version": "1",
"default": "deny",
"tools": {
"update_knowledge": {
"limits": [
{
"counter": "update_knowledge_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_knowledge 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.
Free to start. No card required.
Update an existing knowledge entry. It is categorised as a Write tool in the Opencode Personal Knowledge MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Opencode Personal Knowledge MCP server in PolicyLayer and add a rule for update_knowledge: 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 Opencode Personal Knowledge. Nothing to install.
update_knowledge 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 update_knowledge 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 update_knowledge. 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.
update_knowledge is provided by the Opencode Personal Knowledge MCP server (nocturnlabs/opencode-personal-knowledge). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Opencode Personal Knowledge, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
15 Opencode Personal Knowledge tools catalogued and risk-classified — across an index of 43,000+ MCP servers.