AI agents invoke start_session to trigger actions in Vivado. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
Session initiation on an EDA tool is an Execute operation because it triggers activation of the Vivado environment and potentially subsequent operations on FPGA designs. While the description is empty, the context (vivado-mcp controlling Vivado, sibling tools like generate_bitstream and check_bitstream_readiness) confirms this starts external processes whose effects depend on the session state and subsequent tool…
From the tool's definition Tool name 'start_session' on a Vivado EDA server that 'provides tools to control Xilinx Vivado' and 'including session management'. Starting a session with an EDA tool initiates control of external hardware design and compilation processes.
Documented attack patterns abuse exactly the kind of access start_session gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Vivado, and nothing reaches the server without passing your rules. This is the rule we recommend for start_session:
{
"version": "1",
"default": "deny",
"tools": {
"start_session": {
"limits": [
{
"counter": "start_session_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}start_session stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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start_session. It is categorised as a Execute tool in the Vivado MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Vivado MCP server in PolicyLayer and add a rule for start_session: 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 Vivado. Nothing to install.
start_session is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the start_session 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 start_session. 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.
start_session is provided by the Vivado MCP server (mapleleavessssssss-wq/vivado-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Vivado, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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27 Vivado tools catalogued and risk-classified — across an index of 43,000+ MCP servers.