eth_getFeeHistory

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

With no annotations, the description fully discloses behavior: it is a read-only historical query, returns specific fields (baseFeePerGas, gasUsedRatio, etc.), lists possible errors (InvalidParams, InternalError), and mentions the underlying API (Infura). This provides sufficient transparency for safe usage.

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 well-organized into sections (Args, Returns, Examples, Errors), concise with no wasted words, and front-loaded with the main purpose. Examples provide concrete usage patterns. Every sentence adds value.

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?

The description covers purpose, parameter formats, return structure, examples, and errors. It lacks mention of the response_format parameter (though schema covers it), but otherwise is complete for a read-only tool with no output schema. The examples aid in understanding complex parameters like rewardPercentiles.

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%, but the description adds meaningful details beyond the schema: blockCount requires hex format (e.g., '0x4'), newestBlock can be 'latest', 'pending', or hex, rewardPercentiles is an array of numbers, and network defaults to 'mainnet'. Examples further clarify parameter use. The response_format parameter is not described, but schema already covers 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?

The description clearly states 'Get historical gas fee data for EIP-1559 fee estimation.' This specifies the action (get), resource (historical gas fee data), and context (for EIP-1559 fee estimation), distinguishing it from siblings like eth_getGasPrice which returns current gas price.

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 implies usage for fee estimation, but provides no explicit guidance on when to use this tool versus alternatives (e.g., eth_getGasPrice for current price, other eth_call for data). No when-not-to-use or exclusion criteria are given.

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