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

The annotations already provide readOnlyHint=true and openWorldHint=true, indicating a safe read operation. The description adds beyond this by specifying the return format ('full block object with transaction hashes'), which describes the output behavior without contradicting the annotations.

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 no redundant words. It front-loads the purpose and then provides a concise usage example, effectively earning its place without extra fluff.

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 read-only tool with a single parameter and no output schema, the description covers the key aspects: purpose, parameter format, and return type. It is complete enough for an agent to invoke correctly, though it does not cover potential edge cases (e.g., invalid block number) which are not essential here.

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 input schema already provides 100% coverage for the 'block' parameter, detailing hex format and valid tags. The description repeats part of this ('Use hex block number or latest') without adding new semantic information beyond what the schema states, so it meets the baseline for high schema coverage.

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 the action ('Get block data'), the resource ('block data'), and the scope ('on Mezo'). It also specifies the input format (hex block number or 'latest') and the return type ('full block object with transaction hashes'), which distinguishes it from chain-specific siblings like eth_get_block or btc_get_block.

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 phrase 'on Mezo' clearly situates the tool within the Mezo chain, providing context for when to use it over other chain-specific tools. However, it does not explicitly mention alternatives or exclusions (e.g., 'for Ethereum use eth_get_block'), so it lacks an explicit when-not statement but still offers clear usage context.

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