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

Annotations already mark it readOnly/openWorld, but the description goes well beyond them: per-call cost and payment rail ($0.003 USDC, x402), what is returned on failure (decoded revert reason), what is returned on success (decoded return value, gas units, fee in native coin and USD), and that it encodes signature+args for you. That is exactly the operating context an agent needs before invoking.

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?

Four sentences, front-loaded: purpose+mechanism, then returns, then input modes, then cost. No filler, and the most decision-relevant facts (what it is, what it costs) lead and trail appropriately.

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?

There is no output schema, so the description must carry the return contract, and it does: success/failure, decoded revert reason, decoded return value, gas units, and fee in native coin and USD. Combined with the schema's chain/default documentation, an agent has everything needed to call and interpret this tool.

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 86% (above the 80% baseline of 3), and the description adds the key relationship the schema only implies: you either pass raw calldata via data, or pass signature + args and the service encodes it. It also notes the return value is decoded only when a signature is supplied, which is meaningful beyond the field docs.

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+resource ("Dry-run a transaction") and even the mechanism ("eth_call + gas estimate at the latest block"). The phrase "before you send it" implicitly separates it from send/build tools, but no sibling such as tx_explain or rpc is named, so differentiation is inferred rather than stated.

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?

"Dry-run a transaction before you send it" gives clear timing context for when to reach for this tool. It stops short of naming alternatives (e.g. when to use tx_explain or rpc instead) or stating exclusions such as already-mined transactions.

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