evaluate_expression
Evaluate a GDScript expression in the editor or running game context
This record as markdown: /tools/keeveeg-godot-mcp/evaluate-expression.md
What evaluate_expression does on Godot
AI agents invoke evaluate_expression to trigger actions in Godot. 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.
| Parameter | Type | Required | Description |
|---|---|---|---|
context | string | — | Context to evaluate in (default: editor) |
expression | string | Yes | GDScript expression to evaluate |
Parameters from the server's own tool schema.
Why evaluate_expression is rated High
This tool executes arbitrary GDScript code in either the Godot editor or a running game. Arbitrary code execution can have wide-ranging effects depending on what expressions are evaluated, including file system access, process spawning, or game state manipulation. This is clearly Execute category with high severity due to the arbitrary code execution surface.
From the tool's definition Evaluate a GDScript expression in the editor or running game context
Risk signalsAccepts freeform code/query input (expression)
Attacks that exploit this kind of access
The rule that runs evaluate_expression safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Godot, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For evaluate_expression, this is the rule to start with:
evaluate_expression 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Godot, apply this rule, and every evaluate_expression call is checked against it from then on.
Questions about evaluate_expression
Evaluate a GDScript expression in the editor or running game context. It is categorised as a Execute tool in the Godot MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
evaluate_expression accepts 2 parameters: context, expression. Required: expression. The full parameter table on this page comes from the server's own tool schema.
Register the Godot MCP server in PolicyLayer and add a rule for evaluate_expression: 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 Godot. Nothing to install.
evaluate_expression 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 evaluate_expression 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 evaluate_expression. 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.
evaluate_expression is provided by the Godot MCP server (@keeveeg/godot-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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