assemble_prompt

THE RISK

Low Risk

Why assemble_prompt needs a policy

This tool retrieves and assembles existing prompt/configuration data without side effects. It orchestrates information gathering (reading from other tools/schemas) to construct a system prompt, which is a read-only operation. The lack of action words like 'create', 'modify', 'delete', 'execute', or 'run' confirms this is a Read category tool with low severity risk.

From the tool's definition Tool name 'assemble_prompt' and description 'Assembles the complete system prompt by orchestrating all' indicate data retrieval and composition of prompt/configuration information.

Documented attack patterns abuse exactly the kind of access assemble_prompt gives an agent:

POLICY

How to control assemble_prompt

PolicyLayer is an MCP gateway — it sits between your AI agents and 3DCityDB MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for assemble_prompt:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "assemble_prompt": {}
  }
}

assemble_prompt is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register 3DCityDB MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More 3DCityDB MCP Server tools

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All 14 3DCityDB MCP Server tools →

Read tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about assemble_prompt

What does the assemble_prompt tool do? +

Assembles the complete system prompt by orchestrating all. It is categorised as a Read tool in the 3DCityDB MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on assemble_prompt? +

Register the 3DCityDB MCP Server MCP server in PolicyLayer and add a rule for assemble_prompt: 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 3DCityDB MCP Server. Nothing to install.

What risk level is assemble_prompt? +

assemble_prompt is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit assemble_prompt? +

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

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

assemble_prompt is provided by the 3DCityDB MCP Server MCP server (tum-gis/3dcitydb-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every 3DCityDB MCP Server tool call.

Start from 3DCityDB MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →