generate_caption

Server Posteverywhere posteverywhere/mcp

Category Write

Risk class Medium

Parameters 00 required

WHAT IT DOES

What generate_caption does on Posteverywhere

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

WHY IT NEEDS A POLICY

Why generate_caption needs a policy

An AI agent can call generate_caption faster than any human can review — one bad instruction and it creates or modifies resources in Posteverywhere by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

generate_caption Rate-limited

generate_caption 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": {
    "generate_caption": {
      "limits": [
        {
          "counter": "generate_caption_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Posteverywhere, so you can run agents against it safely.

FAQ

Questions about generate_caption

What does the generate_caption tool do? +

Generate 1-5 AI caption variants for a social media post on PostEverywhere. Provide a topic and optionally tone, platform, length, hashtag/emoji preferences. Captions respect per-platform character limits (X: 280, Bluesky: 300, LinkedIn: 3000, IG: 2200, FB: 5000, etc) and follow platform conventions. Costs 1 AI credit per caption returned. Companion to generate_image — together they let you compose a complete post in two calls. It is categorised as a Write tool in the Posteverywhere MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on generate_caption? +

Register the Posteverywhere MCP server in PolicyLayer and add a rule for generate_caption: 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 Posteverywhere. Nothing to install.

What risk level is generate_caption? +

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

Can I rate-limit generate_caption? +

Yes. Add a rate_limit block to the generate_caption 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 generate_caption completely? +

Set action: deny in the PolicyLayer policy for generate_caption. 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 generate_caption? +

generate_caption is provided by the Posteverywhere MCP server (posteverywhere/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.