Estimate the fees for a specific bridge or swap route without committing to execution. Returns a breakdown of gas fees, relayer fees, and total cost impact. Use this for comparing route costs or showing users expected fees. For standalone token pricing (not route-specific), use get_token_price in...
AI agents call estimate_fees to retrieve information from Relay MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only operation that retrieves fee estimation data for informational purposes. It has no side effects, does not modify blockchain state, does not execute transactions, and does not move funds. It is purely a query tool for cost analysis before any actual execution occurs.
From the tool's definition Tool description states it "Estimate[s] the fees for a specific bridge or swap route without committing to execution" and "Returns a breakdown of gas fees, relayer fees, and total cost impact." The tool explicitly does not commit to execution and only…
Attacks that exploit this kind of access
Estimate the fees for a specific bridge or swap route without committing to execution. Returns a breakdown of gas fees, relayer fees, and total cost impact. Use this for comparing route costs or showing users expected fees. For standalone token pricing (not route-specific), use get_token_price instead. ${AMOUNT_ENCODING} ${CHAIN_ID_FORMAT}. It is categorised as a Read tool in the Relay MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Relay MCP Server MCP server in PolicyLayer and add a rule for estimate_fees: 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 Relay MCP Server. Nothing to install.
estimate_fees 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_fees 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_fees. 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_fees is provided by the Relay MCP Server MCP server (relayprotocol/relay-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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