Change a function/method signature (add/remove/rename/reorder parameters) and update all call sites. Dry-run by default (safe preview). Modifies source files. Use plan_refactoring with type=
AI agents use change_signature to create or update resources in Trace — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Trace environment.
This tool modifies source files by changing function/method signatures and updating all call sites across the codebase. While it has a dry-run default making it reversible in principle, the actual execution modifies potentially many source files simultaneously. This is a Write operation (reversible modification) rather than Destructive since changes can be undone via version control.
From the tool's definition Change a function/method signature (add/remove/rename/reorder parameters) and update all call sites. Dry-run by default (safe preview). Modifies source files.
Documented attack patterns abuse exactly the kind of access change_signature gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Trace, and nothing reaches the server without passing your rules. This is the rule we recommend for change_signature:
{
"version": "1",
"default": "deny",
"tools": {
"change_signature": {
"limits": [
{
"counter": "change_signature_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}change_signature stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Change a function/method signature (add/remove/rename/reorder parameters) and update all call sites. Dry-run by default (safe preview). Modifies source files. Use plan_refactoring with type=. It is categorised as a Write tool in the Trace MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Trace MCP server in PolicyLayer and add a rule for change_signature: 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 Trace. Nothing to install.
change_signature is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the change_signature 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 change_signature. 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.
change_signature is provided by the Trace MCP server (nikolai-vysotskyi/trace-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 178 Trace tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
178 Trace tools catalogued and risk-classified — across an index of 42,500+ MCP servers.