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

Annotations already declare read-only, idempotent and open-world, so the description goes beyond by adding caching behavior (up to 30 s), a bad-chain 422 that occurs before payment and is not charged, typical latency under 1 s, and pricing. These are genuinely decision-relevant operational traits, though the return shape is only lightly touched.

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?

Front-loads the core purpose, follows with sibling routing, then operational facts. Dense and mostly waste-free, though the pricing/free-tier/docs tail is slightly listy and could be trimmed.

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?

With an output schema present and annotations covering the safety profile, the description supplies everything else an agent needs: supported chains, caching, error semantics, latency and cost. Nothing required to invoke it correctly is missing.

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?

There is a single parameter with 100% schema coverage and an enum that already documents the allowed chains. The description restates the chain set but adds no format or syntax meaning beyond what the schema provides, so the 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?

States a specific verb and resource (latest block number, timestamp, age) and scopes it to three named chains. It actively distinguishes itself from siblings by pointing to get_block for the full header and get_chain_info for chain id and 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?

Explicitly routes the agent: 'For the full header use get_block; for chain id and gas price use get_chain_info.' It also states scope limits (Ethereum, Base and Robinhood only), so both when-to-use and when-not-to-use are covered.

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