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

Beyond the annotations it discloses billing mechanics ($0.01/call via x402 USDC or card key, first 25 free, failed calls free), which explains the otherwise surprising idempotentHint=false, and clarifies that repeats are not free. It also confirms the operation is compute-only and changes nothing, reinforcing destructiveHint=false with concrete meaning, plus describes the return payload shape.

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 purpose and return contents, then usage routing, then billing, so the highest-value information comes first. It is dense and slightly crowded in one paragraph — the pricing/credits clauses could be trimmed — but nearly every clause carries 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 fully compensates by enumerating the returned fields and summary statistics. It also covers the cost model and the read-only guarantee, leaving nothing an agent needs in order to call this correctly or estimate its cost.

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% and the single 'blocks' parameter already carries the 5-100 range and default 20 in its description. The tool description largely restates that range and adds only a trivial invocation example (blocks=20), which is the expected baseline when the schema does the work.

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 (gas price history on Celo via eth_feeHistory) and enumerates exactly what is returned: base fee in gwei per block, block fullness, 10th/50th/90th percentile priority fees, and low/average/high base fee over the window. It explicitly separates itself from the sibling celo_gas ('for the current price alone use celo_gas'), so an agent can disambiguate without opening either 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?

Gives three concrete decision contexts (judge whether fees are rising, pick a priority fee, time a transaction) and an explicit alternative with the condition that selects it (celo_gas for the current price alone). No when-to-use inference is required.

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