MCP Tool Reference Low Risk

list_cluster_sizes

List available cluster sizes and pricing

Part of the PlanetScale MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.

WHEN AI AGENTS USE THIS TOOL

AI agents call list_cluster_sizes to retrieve information from PlanetScale without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions — but you may still want rate limits to control API costs.

WHY ENFORCE A POLICY ON LIST_CLUSTER_SIZES

Even though list_cluster_sizes only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.

RECOMMENDED POLICY

Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.

planetscale.yaml
tools:
  list_cluster_sizes:
    rules:
      - action: allow

See the full PlanetScale policy for all 5 tools.

DETAILS

Tool Name

list_cluster_sizes

Category

Read

Risk Level

Low

MORE PLANETSCALE TOOLS

SIMILAR READ TOOLS ON OTHER SERVERS

RELATED READING

FREQUENTLY ASKED QUESTIONS

What does the list_cluster_sizes tool do?

List available cluster sizes and pricing. It is categorised as a Read tool in the PlanetScale MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_cluster_sizes?

Add a rule in your Intercept YAML policy under the tools section for list_cluster_sizes. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the PlanetScale MCP server.

What risk level is list_cluster_sizes?

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

Can I rate-limit list_cluster_sizes?

Yes. Add a rate_limit block to the list_cluster_sizes rule in your Intercept 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 list_cluster_sizes completely?

Set action: deny in the Intercept policy for list_cluster_sizes. 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 list_cluster_sizes?

list_cluster_sizes is provided by the PlanetScale MCP server (planetscale-mcp). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.

ENFORCE POLICIES ON PLANETSCALE

Open source. One binary. Zero dependencies.