set_custom_field

SERVERHuly SOURCE@firfi/huly-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/io-github-dearlordylord-huly-mcp/set-custom-field.md

WHAT IT DOES

What set_custom_field does on Huly

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

RISK

Why set_custom_field is rated Medium

This tool creates or modifies data reversibly. It updates custom field values on documents in Huly, which is a write operation. While it does not delete or destroy data, it does alter existing records. The severity is high because custom field modifications on documents in a project management/collaboration system could affect workflows, approvals, or business logic if misused by an agent without proper safeguards.

From the tool's definition "Set a custom field value on a document" - the tool modifies data on an existing document by setting field values.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs set_custom_field safely

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

set_custom_field Rate-limited

set_custom_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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_custom_field": {
      "limits": [
        {
          "counter": "set_custom_field_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 Huly, apply this rule, and every set_custom_field call is checked against it from then on.

FAQ

Questions about set_custom_field

What does the set_custom_field tool do? +

Set a custom field value on a document. Requires the document ID, class, field ID (from list_custom_fields), and value. Values are parsed before Huly writes: numbers from numeric strings, booleans from. It is categorised as a Write tool in the Huly 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_custom_field? +

Register the Huly MCP server in PolicyLayer and add a rule for set_custom_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 Huly. Nothing to install.

What risk level is set_custom_field? +

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

Can I rate-limit set_custom_field? +

Yes. Add a rate_limit block to the set_custom_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.

How do I block set_custom_field completely? +

Set action: deny in the PolicyLayer policy for set_custom_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.

What MCP server provides set_custom_field? +

set_custom_field is provided by the Huly MCP server (@firfi/huly-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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