replace_once

Safely replace one exact text occurrence in a text file.

SERVERMapi Agent Memory SOURCEcabo0m/mapi-agent-memory

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/mapi-agent-memory/replace-once.md

WHAT IT DOES

What replace_once does on Mapi Agent Memory

AI agents use replace_once to create or update resources in Mapi Agent Memory, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mapi Agent Memory environment.

RISK

Why replace_once is rated Medium

This tool modifies file contents by replacing text, making it a Write operation rather than Read. It is not Destructive because it replaces a single occurrence (reversible via version control or undo) rather than permanently deleting data.

From the tool's definition Tool description states 'replace one exact text occurrence in a text file', which is a text modification operation. The word 'replace' indicates content is being altered and potentially overwritten.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs replace_once safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Mapi Agent Memory, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For replace_once, this is the rule to start with:

replace_once Rate-limited

replace_once 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "replace_once": {
      "limits": [
        {
          "counter": "replace_once_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Mapi Agent Memory, apply this rule, and every replace_once call is checked against it from then on.

FAQ

Questions about replace_once

What does the replace_once tool do? +

Safely replace one exact text occurrence in a text file. It is categorised as a Write tool in the Mapi Agent Memory MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on replace_once? +

Register the Mapi Agent Memory MCP server in PolicyLayer and add a rule for replace_once: 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 Mapi Agent Memory. Nothing to install.

What risk level is replace_once? +

replace_once is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit replace_once? +

Yes. Add a rate_limit block to the replace_once 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.

How do I block replace_once completely? +

Set action: deny in the PolicyLayer policy for replace_once. 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.

What MCP server provides replace_once? +

replace_once is provided by the Mapi Agent Memory MCP server (cabo0m/mapi-agent-memory). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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