Returns the slot of the lowest confirmed block available.
AI agents call get_first_available_block to retrieve information from Model Context Protocol Server for Solana Client without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Even though get_first_available_block only reads data, uncontrolled read access leaks sensitive information and racks up API costs — an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
Returns the slot of the lowest confirmed block available. It is categorised as a Read tool in the Model Context Protocol Server for Solana Client MCP Server, which means it retrieves data without modifying state.
Register the Model Context Protocol Server for Solana Client MCP server in PolicyLayer and add a rule for get_first_available_block: 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 Model Context Protocol Server for Solana Client. Nothing to install.
get_first_available_block is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get_first_available_block 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.
Set action: deny in the PolicyLayer policy for get_first_available_block. 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.
get_first_available_block is provided by the Model Context Protocol Server for Solana Client MCP server (tywenk/mcp-sol). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.