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

Goes well beyond the annotations by disclosing billing ($0.01/call via x402 USDC or card key, first 25 free, failed calls free) and reiterating the no-side-effect guarantee; 'repeats are not free' is consistent with idempotentHint=false. The only flaw is the inaccurate 'Takes no input' claim, since the schema exposes an optional `only` filter.

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 returned values and the usage decision, then pricing. Dense but nearly every clause earns its place; the 'Takes no input' clause is the one piece of wasted, and incorrect, text.

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 does the work of explaining return values (gas price, base fee, priority fee, transfer cost) and cost/authorization model, which is exactly what an agent needs for a zero-required-param read. It falls short only on the optional `only` parameter, which it denies exists.

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 the baseline would be 3, but the description affirmatively states 'Takes no input' while the schema defines an optional `only` key-filtering parameter. That statement actively misleads the agent about the tool's one parameter rather than merely omitting it.

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 ('Current gas price on Celo (eth_gasPrice)') and enumerates the exact returned fields: gas price, base fee, suggested priority fee in gwei, plus the cost of a 21,000-gas CELO transfer. It clearly separates itself from celo_gas_history (historical) and celo_receipt (fee actually paid), so an agent can pick it without opening a schema.

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 names the use case ('before sending a transaction or to decide whether to wait') and the exclusion with a named alternative ('for the fee a past transaction actually paid use celo_receipt'). When-to-use and when-not-to-use are both covered.

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