AI agents use write_code_file to create or update resources in CodeSavant — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your CodeSavant environment.
This tool creates or modifies code files reversibly. While it can alter source code (which is critical infrastructure in some contexts), the write operation itself is reversible—files can be restored via version control or the get_code_history/revert_to_version tools available on the same server. It does not delete data (which would be Destructive) or execute arbitrary commands (which would be Execute).
From the tool's definition Tool description states: 'Write or update specific lines in a code file'. The action is explicitly a write/update operation on code files.
Documented attack patterns abuse exactly the kind of access write_code_file gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and CodeSavant, and nothing reaches the server without passing your rules. This is the rule we recommend for write_code_file:
{
"version": "1",
"default": "deny",
"tools": {
"write_code_file": {
"limits": [
{
"counter": "write_code_file_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}write_code_file 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.
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Write or update specific lines in a code file. It is categorised as a Write tool in the CodeSavant MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the CodeSavant MCP server in PolicyLayer and add a rule for write_code_file: 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 CodeSavant. Nothing to install.
write_code_file 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 write_code_file 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 write_code_file. 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.
write_code_file is provided by the CodeSavant MCP server (twolven/mcp-codesavant). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from CodeSavant, 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.
7 CodeSavant tools catalogued and risk-classified — across an index of 43,000+ MCP servers.