dbg_set_variable
Change a variable's value in a stopped frame (DAP setVariable). DESTRUCTIVE: mutates live program state — confirm with the user and keep this gated. variables_ref is the container's variablesReference (from dbg_scopes, or a complex entry in dbg_variables), name is the variable's name within it, a...
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What dbg_set_variable does on Breakpoint
AI agents invoke dbg_set_variable to trigger actions in Breakpoint. 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 |
|---|---|---|---|
name | string | Yes | Variable name within that container |
value | string | Yes | New value as a GDScript literal/expression |
confirm | boolean | — | Auto-approve this mutation (skip the confirmation prompt) |
variables_ref | integer | Yes | variablesReference of the containing scope/variable (from dbg_scopes or dbg_variables) |
Parameters from the server's own tool schema.
Why dbg_set_variable is rated High
This tool mutates live program state by changing variable values during a debug session. While labeled 'DESTRUCTIVE' in the description, it is not deleting or irreversibly destroying data in the traditional sense — it modifies runtime state of a running/paused program. This is best classified as Execute since it triggers an external operation (DAP setVariable) that affects live program execution state.
From the tool's definition Change a variable's value in a stopped frame (DAP setVariable). DESTRUCTIVE: mutates live program state
Attacks that exploit this kind of access
The rule that runs dbg_set_variable safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Breakpoint, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For dbg_set_variable, this is the rule to start with:
dbg_set_variable 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 Breakpoint, apply this rule, and every dbg_set_variable call is checked against it from then on.
Questions about dbg_set_variable
Change a variable's value in a stopped frame (DAP setVariable). DESTRUCTIVE: mutates live program state — confirm with the user and keep this gated. variables_ref is the container's variablesReference (from dbg_scopes, or a complex entry in dbg_variables), name is the variable's name within it, and value is the new value as a GDScript literal/expression. Only meaningful while stopped at a breakpoint. It is categorised as a Execute tool in the Breakpoint MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
dbg_set_variable accepts 4 parameters: name, value, confirm, variables_ref. Required: name, value, variables_ref. The full parameter table on this page comes from the server's own tool schema.
Register the Breakpoint MCP server in PolicyLayer and add a rule for dbg_set_variable: 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 Breakpoint. Nothing to install.
dbg_set_variable 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 dbg_set_variable 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 dbg_set_variable. 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.
dbg_set_variable is provided by the Breakpoint MCP server (breakpoint-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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