Create a new P256 access key (session key) for delegated signing.
AI agents use create_access_key to create or update resources in Tempo — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Tempo environment.
This tool creates a new cryptographic access key that enables delegated signing authority. While it is a Write operation (creating a resource), it carries high severity because a misused or maliciously created session key could allow an attacker to delegate signing rights on the blockchain, potentially enabling unauthorized transactions or payments on the Tempo stablecoin platform.
From the tool's definition Create a new P256 access key (session key) for delegated signing
Documented attack patterns abuse exactly the kind of access create_access_key gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Tempo, and nothing reaches the server without passing your rules. This is the rule we recommend for create_access_key:
{
"version": "1",
"default": "deny",
"tools": {
"create_access_key": {
"limits": [
{
"counter": "create_access_key_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_access_key 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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Create a new P256 access key (session key) for delegated signing. It is categorised as a Write tool in the Tempo MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Tempo MCP server in PolicyLayer and add a rule for create_access_key: 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 Tempo. Nothing to install.
create_access_key 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 create_access_key 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 create_access_key. 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.
create_access_key is provided by the Tempo MCP server (arome3/tempo-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Tempo, 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.
61 Tempo tools catalogued and risk-classified — across an index of 43,000+ MCP servers.