Commonly used to fetch the historical native, fungible (ERC20), and non-fungible (ERC721 & ERC1155) tokens held by an address at a given block height or date
AI agents call getHistoricalBalance to retrieve information from Somnia 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 historical balance information from the blockchain without modifying, deleting, or executing any operations. It queries existing data (native tokens, ERC20, ERC721, ERC1155 balances) at specific points in time. No side effects occur from calling this tool.
From the tool's definition Tool description states it is 'used to fetch' historical token balances and holdings data at a given block height or date.
Attacks that exploit this kind of access
Commonly used to fetch the historical native, fungible (ERC20), and non-fungible (ERC721 & ERC1155) tokens held by an address at a given block height or date. It is categorised as a Read tool in the Somnia MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Somnia MCP Server MCP server in PolicyLayer and add a rule for getHistoricalBalance: 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 Somnia MCP Server. Nothing to install.
getHistoricalBalance 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 getHistoricalBalance 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 getHistoricalBalance. 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.
getHistoricalBalance is provided by the Somnia MCP Server MCP server (vastavikadi/somnia-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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