add_query_param · TinyFn MCP: Risk & Policy

WHAT IT DOES

What add_query_param does on TinyFn

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

PARAMETERS

Parameter	Type	Required	Description
`key`	string	Yes	Parameter key
`url`	string	Yes	URL to modify
`value`	string	Yes	Parameter value

Parameters from the server's own tool schema.

WHY IT NEEDS A POLICY

Why add_query_param needs a policy

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

Risk signalsAccepts URL/endpoint input (url)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_query_param Rate-limited

add_query_param 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": {
    "add_query_param": {
      "limits": [
        {
          "counter": "add_query_param_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 TinyFn, so you can run agents against it safely.

FAQ

Questions about add_query_param

What does the add_query_param tool do? +

Add a query parameter to a URL. It is categorised as a Write tool in the TinyFn MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does add_query_param accept? +

add_query_param accepts 3 parameters: key, url, value. Required: key, url, value. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on add_query_param? +

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

What risk level is add_query_param? +

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

Can I rate-limit add_query_param? +

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

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

add_query_param is provided by the TinyFn MCP server (https://api.tinyfn.io/mcp/all/). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.