Returns the number of the most recent block
AI agents call eth_blockNumber to retrieve information from EVM MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves current blockchain state information (the latest block number) without side effects, making it a pure Read operation. The blast radius of misuse is minimal—an attacker cannot cause harm beyond gathering public blockchain information that is already available to anyone querying the network.
From the tool's definition Tool name 'eth_blockNumber' and description 'Returns the number of the most recent block' indicate a read-only query operation that retrieves blockchain metadata without modifying state or executing code.
Attacks that exploit this kind of access
Returns the number of the most recent block. It is categorised as a Read tool in the EVM MCP Server MCP Server, which means it retrieves data without modifying state.
Register the EVM MCP Server MCP server in PolicyLayer and add a rule for eth_blockNumber: 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 EVM MCP Server. Nothing to install.
eth_blockNumber 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 eth_blockNumber 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 eth_blockNumber. 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.
eth_blockNumber is provided by the EVM MCP Server MCP server (jamesanz/evm-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
eth_blockNumber is one line of EVM MCP Server's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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