Estimate the gas necessary to complete a transaction without submitting it to the network.
AI agents call estimate-gas to retrieve information from MetaMask MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only retrieves gas cost estimates and does not modify blockchain state, execute transactions, transfer funds, or trigger external operations. It is a non-destructive informational query similar to other Read operations on the server (get-account, get-block, get-block-number, get-chain-id). The explicit exclusion of network submission confirms no state mutation occurs.
From the tool's definition Tool description states it 'estimate[s] the gas necessary...without submitting it to the network,' which is a query/retrieval operation with no side effects or state changes.
Documented attack patterns abuse exactly the kind of access estimate-gas gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MetaMask MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for estimate-gas:
{
"version": "1",
"default": "deny",
"tools": {
"estimate-gas": {}
}
}estimate-gas is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Estimate the gas necessary to complete a transaction without submitting it to the network. It is categorised as a Read tool in the MetaMask MCP MCP Server, which means it retrieves data without modifying state.
Register the MetaMask MCP server in PolicyLayer and add a rule for estimate-gas: 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 MetaMask MCP. Nothing to install.
estimate-gas 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 estimate-gas 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 estimate-gas. 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.
estimate-gas is provided by the MetaMask MCP server (xiawpohr/metamask-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MetaMask MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
29 MetaMask MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.