evm_tx

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full behavioral burden and does much of it: it discloses the possible status values (success, failed, pending, not_found), the cost ($0.002 USDC per call), and p99 latency of 2500ms — all non-obvious operational traits. It omits auth requirements and error/quota behavior, but for a read-only chain lookup this is strong disclosure.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action and scope, then return fields, then a compact 'Params:' and 'Cost:/Latency:' block — no filler sentences. The return-field enumeration is long but earns its place given there is no output schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description takes on the return contract by listing status, block, confirmations, timestamp, addresses, value, gas, fee, method id and decoded ERC20 transfers. Combined with parameter defaults and cost/latency, an agent has everything needed to call and interpret it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 50% (only 'hash' is documented in-schema; 'chain' has just an enum and default). The description compensates by restating that hash is a required 0x transaction hash and that chain defaults to 'base' with the two alternatives, adding meaning beyond the bare enum.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Look up a transaction') plus the exact scope (Base, Ethereum, IOTA EVM mainnet), which cleanly separates it from the non-EVM chain siblings like btc_tx, tron_tx, sui_tx and iota_tx. It also enumerates the returned fields, so an agent knows precisely what question this tool answers.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives a concrete usage context — 'Useful to confirm that a payment arrived' — which tells the agent when to reach for it. It stops short of naming alternatives (evm_balance, erc20_transfers, token_flows) or stating when not to use it, so it is clear context without exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.