AI agents call session_prime to retrieve information from Project Tessera without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and loads contextual information into the session for reference—a read-only operation with no side effects. It does not create, modify, delete, or execute code. The scope is limited to populating context, making it a Read-category tool with low severity.
From the tool's definition The tool 'session_prime' is described as priming the session 'with recent context.' In the context of a memory/knowledge system, 'prime' means to preload or retrieve context for use.
Documented attack patterns abuse exactly the kind of access session_prime gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Project Tessera, and nothing reaches the server without passing your rules. This is the rule we recommend for session_prime:
{
"version": "1",
"default": "deny",
"tools": {
"session_prime": {}
}
}session_prime is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Prime the session with recent context. It is categorised as a Read tool in the Project Tessera MCP Server, which means it retrieves data without modifying state.
Register the Project Tessera MCP server in PolicyLayer and add a rule for session_prime: 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 Project Tessera. Nothing to install.
session_prime is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the session_prime 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 session_prime. 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.
session_prime is provided by the Project Tessera MCP server (besslframework-stack/project-tessera). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Project Tessera, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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43 Project Tessera tools catalogued and risk-classified — across an index of 43,000+ MCP servers.