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

With no annotations, the description carries the full burden and does well: it discloses the full evidence bundle returned, notes staleness of the chain head, gives economic cost ($0.02/call over x402 in USDC), and states no API key or account is needed. It never explicitly says the transaction is not broadcast/signed, nor what happens when canSend is false, which keeps it short of a 5 for a tool an agent may act on.

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?

The trigger condition is front-loaded and the payment facts are placed last where they belong. The middle is one very long clause chaining seven return values, which is dense but each item corresponds to a distinct decision input, so little is redundant.

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?

For a 5-parameter tool with no annotations and no output schema, the description compensates well by narrating the return payload in prose. Remaining gaps are the exact response shape (how canSend and the supporting fields are structured) and any failure or staleness-threshold behavior, which matter since there is no output schema to fall back on.

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 100%, so all five parameters (from, to, data, value, chain) are already documented in the input schema and the baseline of 3 applies. The description adds only indirect signal — 'gas this exact transaction needs' hints that data/value affect the estimate — but gives no format or default guidance beyond what the schema states.

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?

Opens with a concrete decision verb-phrase — 'answers canSend' — plus an enumerated list of the facts it returns (balance, gas, cost, revert simulation, nonce, contract detection, head staleness). It explicitly positions itself against the granular read siblings by stating 'Replaces five separate reads,' so an agent can tell it apart from evm_balance, evm_gas, evm_nonce, or evm_estimate_gas.

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?

'Use when an agent is about to sign a transaction and must decide whether it will go through right now' gives a precise trigger condition. The 'replaces five separate reads' line routes the agent away from composite-vs-granular confusion, though it does not name the specific alternatives (evm_call, evm_estimate_gas) or state a when-not case such as post-broadcast status checking.

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