AI agents invoke safe_tcl 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.
The server description explicitly mentions 'Tcl execution' as a core capability. The tool name 'safe_tcl' strongly implies execution of Tcl scripts/commands within Vivado. Despite the 'safe' qualifier, arbitrary Tcl execution in an EDA environment can have significant effects including modifying project files, running synthesis/implementation, or even executing system commands.
From the tool's definition Tool name 'safe_tcl' on a server described as providing 'Tcl execution' capabilities for controlling Xilinx Vivado EDA
Documented attack patterns abuse exactly the kind of access safe_tcl 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 safe_tcl:
{
"version": "1",
"default": "deny",
"tools": {
"safe_tcl": {
"limits": [
{
"counter": "safe_tcl_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}safe_tcl 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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safe_tcl. 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 safe_tcl: 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.
safe_tcl 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 safe_tcl 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 safe_tcl. 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.
safe_tcl 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.
Free to start. No card required.
27 Vivado tools catalogued and risk-classified — across an index of 43,000+ MCP servers.