get-username-casts · Farcaster MCP Server MCP: Risk & Policy

WHAT IT DOES

What get-username-casts does on Farcaster MCP Server

AI agents call get-username-casts to retrieve information from Farcaster MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

WHY IT NEEDS A POLICY

Why get-username-casts needs a policy

This tool retrieves (fetches) casts posted by a specific user from the Farcaster network. The use of 'get' in the name and 'Get' in the description confirm it is a query operation. No data is created, modified, deleted, or used to trigger external actions. The blast radius of misuse is minimal—an agent could retrieve public posts but cannot alter them or access unauthorized data beyond normal API permissions.

From the tool's definition Tool name 'get-username-casts' and description 'Get casts from a specific Farcaster username' indicate data retrieval with no modification or side effects.

Attacks that exploit this kind of access

Questions about get-username-casts

What does the get-username-casts tool do? +

Get casts from a specific Farcaster username. It is categorised as a Read tool in the Farcaster MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on get-username-casts? +

Register the Farcaster MCP Server MCP server in PolicyLayer and add a rule for get-username-casts: 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 Farcaster MCP Server. Nothing to install.

What risk level is get-username-casts? +

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

Can I rate-limit get-username-casts? +

Yes. Add a rate_limit block to the get-username-casts 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 get-username-casts completely? +

Set action: deny in the PolicyLayer policy for get-username-casts. 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 get-username-casts? +

get-username-casts is provided by the Farcaster MCP Server MCP server (manimohans/farcaster-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.