AI agents use add_field to create or update resources in Ast Editor — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Ast Editor environment.
This tool adds a field to code (likely a class or data structure) via AST editing. This is a reversible modification operation—fields can be removed or changed—making it a Write action rather than Destructive. The medium severity reflects that an agent could introduce bugs, break code structure, or add unwanted fields, but the operation itself is not irreversible or catastrophic.
From the tool's definition Tool name 'add_field' combined with sibling tools like 'add_cell', 'add_import', 'add_method', 'add_parameter', and 'add_top_level' which all create or modify code structures reversibly via AST manipulation.
Documented attack patterns abuse exactly the kind of access add_field gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Ast Editor, and nothing reaches the server without passing your rules. This is the rule we recommend for add_field:
{
"version": "1",
"default": "deny",
"tools": {
"add_field": {
"limits": [
{
"counter": "add_field_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_field 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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add_field. It is categorised as a Write tool in the Ast Editor MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Ast Editor MCP server in PolicyLayer and add a rule for add_field: 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 Ast Editor. Nothing to install.
add_field 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 add_field 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 add_field. 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.
add_field is provided by the Ast Editor MCP server (kambleakash0/agent-skills). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Ast Editor, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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59 Ast Editor tools catalogued and risk-classified — across an index of 43,000+ MCP servers.