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

With no annotations, the description carries the full behavioral burden. It discloses a genuinely useful trait beyond the schema: the x402 paid model at $0.004 USDC on Base per call, which an agent needs to know before invoking. However, it says nothing about return shape, error behavior, rate limits, or auth requirements.

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?

Two short sentences with no filler, and the core purpose is front-loaded ahead of the pricing note. The first sentence is a bare fragment rather than a sentence, which is a minor structural weakness but keeps the definition tight.

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?

There is no output schema and no annotations, so the description must explain what a caller receives; it never states what a block response contains (header fields, transactions, etc.). For a paid data-fetch tool with zero structured coverage of its result, this is a notable gap.

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 description coverage is 100%, so both parameters are already fully documented in the schema (block accepting decimal/hex/'latest', chain enumerating five networks). The description only restates the accepted block forms and adds that the provider is Alchemy, adding little meaning beyond structured data. Baseline 3 applies.

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 identifies the resource (a block) and its scope (by number or 'latest', on a named chain, sourced via Alchemy), which is enough for an agent to distinguish it from sibling tools that all deal with balances, prices, NFTs, and history. It is a noun fragment rather than a clear verb+resource statement, but the purpose is unambiguous.

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?

There is no explicit when-to-use or when-not-to-use guidance, nor any mention of alternative tools (e.g., cortex_gas_oracle for fee data). The only routing-adjacent signal is the cost disclosure, which acts as an implicit gate but does not tell the agent when this tool is the right choice.

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