fm_run_script_and_assert

THE RISK

High Risk

Why fm_run_script_and_assert needs a policy

The tool executes FileMaker scripts whose effects depend entirely on script arguments and content. While it includes an assertion check (defensive), script execution itself is inherently Execute category because the tool triggers external operations (FileMaker scripts) that can read, write, or delete data depending on script logic.

From the tool's definition Tool description states it 'Runs a FileMaker script', which is code execution. The context describes the server as enabling 'script execution' on FileMaker databases.

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

POLICY

How to control fm_run_script_and_assert

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "fm_run_script_and_assert": {
      "limits": [
        {
          "counter": "fm_run_script_and_assert_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

fm_run_script_and_assert stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

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

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Filemaker tools

Destructive fm_delete_record Delete a FileMaker record by ROWID. Destructive fm_cleanup_test_data Deletes all test records marked with a specific tag. tagField must be an existing text fie Execute fm_run_script Run a FileMaker script. Returns scriptResult with code and resultParameter. Execute fm_run_script_with_globals Sets global fields and runs a script in the SAME Data API session. This makes scripts that Write fm_add_field Add a new field to an existing FileMaker table. SQL-style field types: VARCHAR(n), INT, NU Write fm_create_record Create a new record in a FileMaker table. Write fm_create_table Create a new table in the FileMaker database (schema modification via OData). Write fm_create_test_record Creates a test record with a test tag. tagField must be an existing text field in the FM t

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Go deeper

High-risk tools in Filemaker → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about fm_run_script_and_assert

What does the fm_run_script_and_assert tool do? +

Runs a FileMaker script and checks whether the result code matches the expected value. It is categorised as a Execute tool in the Filemaker MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on fm_run_script_and_assert? +

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

What risk level is fm_run_script_and_assert? +

fm_run_script_and_assert is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit fm_run_script_and_assert? +

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

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

fm_run_script_and_assert is provided by the Filemaker MCP server (joergkoester/mcp-server-filemaker). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Filemaker tool call.

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

CHECK YOUR STACK →