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

Goes well beyond the annotations: revert behavior is a 422 with reason and uncharged, pricing is $0.01/call via x402 USDC or card key with first 25 free and failed calls free, and repeats are billed (consistent with idempotentHint=false). This is exactly the extra context the readOnly/destructive hints cannot convey.

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?

Dense but front-loaded: the estimate/cost purpose comes first, then usage, then error handling and pricing. The pricing/payment sentence is long but each clause (cost, free tier, failed-call policy, non-idempotency) carries distinct decision-relevant information.

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 still specifies the return units (gas, gwei, ETH) and the failure mode (422 with reason). Combined with 100% parameter coverage, 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 100%, so baseline is 3, but the description adds real meaning: value is denominated in ETH, from is only needed when the call depends on the sender (and defaults to an empty address per schema), and it gives a concrete example address for to.

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 (estimate), the resource (gas for a transaction), the chain (Ink), and the underlying RPC method (eth_estimateGas), plus the economic result (cost in gas units, gwei, ETH). This is clearly distinguishable from the sibling ink_gas, which it names.

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?

Explicitly says when to use it ('before sending a transaction or to price a batch') and when not to ('for the gas price alone use ink_gas'). It also tells the agent which fields to supply depending on the scenario (from only when the call depends on the sender).

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