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

Annotations declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds value beyond annotations by disclosing the output format (wei hex string) and network scope. It does not describe rate limits or error behavior, but for a simple read-only getter this is sufficient.

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 description is two sentences, with the first sentence stating the core action and the second providing a use case. Every word earns its place, no fluff or redundancy.

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 simple tool with zero parameters, good annotations, and no output schema, the description is complete: it states what is returned (gas price in wei as hex string), the network, and a typical use case. There is no missing information that would prevent correct invocation.

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?

The tool has no parameters, and the schema is empty with 100% coverage trivially. The description adds no parameter-specific info because none exist, and the baseline for zero-parameter tools is 4. The output format described compensates for the lack of an output schema.

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?

The description uses a specific verb ('Get') and resource ('current gas price on Ethereum mainnet') with output format ('wei (hex string)'), clearly distinguishing it from siblings like mezo_gas_price (different network) and eth_estimate_gas (estimates gas for a transaction, not the current price). It precisely states what the tool does.

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?

The description provides a clear use case ('Use to estimate transaction costs') and specifies the network (Ethereum mainnet), which helps select it over alternatives like mezo_gas_price. However, it does not explicitly mention when not to use it (e.g., for other networks) or contrast with eth_estimate_gas, so it lacks explicit exclusion guidance.

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