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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds valuable context: 'Free, no signup required' and 'no key or payment needed,' which are not in annotations. It also mentions the data source (Etherscan). It stops short of mentioning rate limits or data freshness, keeping it at a 4.

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 front-loaded with the core purpose, followed by a usage example, then explicit when-to-use/when-not, and finally a brief behavior note. Every sentence adds value with no 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, parameterless data retrieval tool with rich annotations and no output schema, the description covers what it does, when to use it, and key behavioral traits (free, no key). It is complete enough for an agent to call it correctly without further information.

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?

With zero parameters, the baseline is 4. The description does not need to explain any parameter semantics, and it correctly focuses on purpose and usage.

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 specifies the resource (Ethereum gas oracle), the data provided (safe/propose/fast gas prices + base fee, in gwei), and the source (Etherscan). It explicitly distinguishes from siblings by stating 'Not for other chains,' making it immediately clear this is not a general blockchain data tool.

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?

It gives explicit when-to-use guidance: 'Use when you need current Ethereum gas prices ... before sending a transaction.' It also states when not to use: 'Not for other chains.' This is clear and actionable.

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