Store or update a BYOK (bring-your-own-key) credential for a marketplace MCP server. The key is encrypted at rest and validated before storing. For n8n: pass the api_key and base_url separately — they will be combined into the required format. For other services: just pass the api_key.
Risk signalsHandles credentials or secrets (api_key) · Accepts URL/endpoint input (base_url)
Part of the Clevername server.
Free to start. No card required.
AI agents use upsert_mcp_credential to create or modify resources in Clevername. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call upsert_mcp_credential repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Clevername.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"upsert_mcp_credential": {
"limits": [
{
"counter": "upsert_mcp_credential_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Clevername policy for all 67 tools.
These attack patterns abuse exactly the kind of access upsert_mcp_credential gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Store or update a BYOK (bring-your-own-key) credential for a marketplace MCP server. The key is encrypted at rest and validated before storing. For n8n: pass the api_key and base_url separately — they will be combined into the required format. For other services: just pass the api_key.. It is categorised as a Write tool in the Clevername MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Clevername MCP server in PolicyLayer and add a rule for upsert_mcp_credential: 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 Clevername. Nothing to install.
upsert_mcp_credential 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 upsert_mcp_credential 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 upsert_mcp_credential. 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.
upsert_mcp_credential is provided by the Clevername MCP server (@clevername/clevername-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 67 Clevername tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.