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

With no annotations, the description must carry the burden of behavioral disclosure. It discloses that success returns a balance, but does not explain failure modes, side effects (though likely read-only), authentication requirements beyond the api_key parameter, or error behavior. This is a moderate gap.

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 first sentence is duplicated verbatim ('Verifies a blockchain address as valid for the blockchain' appears twice), wasting space. The rest is reasonably compact, but the repetition is an unnecessary flaw.

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 relatively simple tool, the description covers core functionality and return type (JSON), and an output schema exists so return details need not be spelled out. However, the blockchain_fk ambiguity and lack of error/edge-case context make it only minimally complete.

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 0%, so the description must compensate. It clarifies 'api_key' and 'address' but gives only a tautological explanation for 'blockchain_fk': 'The blockchain_fk of the supported blockchain.' This leaves the integer foreign key ambiguous – the agent cannot know which blockchains are supported or how to select a valid value.

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 tool's purpose: 'Verifies a blockchain address as valid for the blockchain' – a specific verb and resource. It also adds that it works for any address and returns a balance, which differentiates it from balance-only tools like crypto_balance.

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 'Can be any address on that blockchain' provides clear usage context, implying it's for general address verification without restrictions. No exclusions or alternatives are mentioned, but the context is clear enough for an agent to decide when to use it.

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