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

Annotations already cover readOnlyHint and openWorldHint, but the description adds meaningful context the annotations do not: the returned fields (code size, proxy implementation, token standards) and, critically, that this is a paid call at $0.01 USDC via x402. Disclosing cost is real behavioral value.

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 compact sentences, front-loaded with the core question and the returned attributes, with pricing tacked on at the end. Efficient, though the pricing clause could be better integrated.

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 no output schema, the description takes on the return-value burden and does so by listing the classified fields. It also surfaces the paid nature of the call. Only the address-format and any output structure detail are left implicit.

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 one parameter with 0% schema description coverage, so the description carries the burden. It identifies the input as 'this Base address', but adds no detail on format or meaning beyond the name; the schema's regex pattern is what actually conveys the expected shape.

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 states a specific resource (a Base address) and enumerates what the tool determines: EOA vs contract, code size, proxy implementation, and ERC-20/721/1155 detection. This distinguishes it from balance/token/transfer siblings, though it never names an alternative to route against.

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 frames the use case as a question ('What is this Base address?') which implies when to reach for it, but gives no explicit when-to-use/when-not guidance and never contrasts it with siblings like base_token, base_nft_metadata, or base_balance that an agent must disambiguate from.

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