Update settings for an existing corpus. None args are no-ops.
AI agents use files_corpus_set to create or update resources in M3 Memory — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your M3 Memory environment.
This tool modifies existing configuration or settings for a corpus (indexed document collection), which falls under Write category—it creates or modifies data reversibly. The severity is medium rather than low because misconfiguration of a memory corpus could affect the behavior of all queries against that corpus, potentially degrading agent reasoning or causing data accessibility issues.
From the tool's definition 'Update settings for an existing corpus' indicates modification of configuration or metadata for a persistent data storage entity. This is a reversible write operation that alters state within the memory system.
Documented attack patterns abuse exactly the kind of access files_corpus_set gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and M3 Memory, and nothing reaches the server without passing your rules. This is the rule we recommend for files_corpus_set:
{
"version": "1",
"default": "deny",
"tools": {
"files_corpus_set": {
"limits": [
{
"counter": "files_corpus_set_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}files_corpus_set 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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Update settings for an existing corpus. None args are no-ops. It is categorised as a Write tool in the M3 Memory MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the M3 Memory MCP server in PolicyLayer and add a rule for files_corpus_set: 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 M3 Memory. Nothing to install.
files_corpus_set 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 files_corpus_set 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 files_corpus_set. 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.
files_corpus_set is provided by the M3 Memory MCP server (skynetcmd/m3-memory). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from M3 Memory, 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.
43 M3 Memory tools catalogued and risk-classified — across an index of 43,000+ MCP servers.