set_caption

Set Lightroom caption metadata for selected photos or local_ids.

SERVERLightroom Classic MCP SOURCE4xiomdev/lightroom-classic-mcp

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/4xiomdev-lightroom-classic-mcp/set-caption.md

WHAT IT DOES

What set_caption does on Lightroom Classic MCP

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

RISK

Why set_caption is rated Medium

This tool creates or modifies caption metadata on photos without deletion or destructive effects. While it mutates catalog state, the change is reversible (captions can be edited, cleared, or reverted). Severity is medium because unintended bulk caption changes could clutter metadata, but the impact is confined to that specific metadata field and easily corrected.

From the tool's definition Tool description states it 'Set[s] Lightroom caption metadata' — a metadata write operation. The tool modifies photo properties (captions) in the Lightroom catalog reversibly, with no deletion or irreversible effects.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs set_caption safely

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

set_caption Rate-limited

set_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": {
    "set_caption": {
      "limits": [
        {
          "counter": "set_caption_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 Lightroom Classic MCP, apply this rule, and every set_caption call is checked against it from then on.

FAQ

Questions about set_caption

What does the set_caption tool do? +

Set Lightroom caption metadata for selected photos or local_ids. It is categorised as a Write tool in the Lightroom Classic MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_caption? +

Register the Lightroom Classic MCP server in PolicyLayer and add a rule for set_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 Lightroom Classic MCP. Nothing to install.

What risk level is set_caption? +

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

Can I rate-limit set_caption? +

Yes. Add a rate_limit block to the set_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 set_caption completely? +

Set action: deny in the PolicyLayer policy for set_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 set_caption? +

set_caption is provided by the Lightroom Classic MCP server (4xiomdev/lightroom-classic-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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