Returns current gas prices and estimated costs for common DeFi operations across EVM chains (Ethereum, Arbitrum, Base, BNB Chain) and Solana priority fees, allowing agents to confirm a wallet holds sufficient native gas and to select the cheapest chain for an operation. Covered operations: transf...
Part of the Syenite server.
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AI agents call gas.estimate to retrieve information from Syenite without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though gas.estimate only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"gas.estimate": {}
}
}See the full Syenite policy for all 46 tools.
These attack patterns abuse exactly the kind of access gas.estimate gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Returns current gas prices and estimated costs for common DeFi operations across EVM chains (Ethereum, Arbitrum, Base, BNB Chain) and Solana priority fees, allowing agents to confirm a wallet holds sufficient native gas and to select the cheapest chain for an operation. Covered operations: transfer, erc20_transfer, erc20_approve, swap, bridge, lending_supply, lending_borrow, contract_register — each reported with gas units, cost in native token, and approximate USD cost at current price. For Solana, returns recent prioritization fees in micro-lamports per compute unit (min, median, p75, max) sampled from the last few slots. Optionally filter by chains (array) and operations (array of operation names); defaults to all chains and all operations. Identifies the cheapest chain per operation. USD estimates use approximate native token prices and are indicative, not exact.. It is categorised as a Read tool in the Syenite MCP Server, which means it retrieves data without modifying state.
Register the Syenite MCP server in PolicyLayer and add a rule for gas.estimate: 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 Syenite. Nothing to install.
gas.estimate 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 gas.estimate 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 gas.estimate. 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.
gas.estimate is provided by the Syenite MCP server (@syenite/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 46 Syenite tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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