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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, and the description goes well beyond them: it discloses the pricing model (25 free calls/day, then $0.01 USDC via x402), the real-money consequence of misuse, and the scope of returned address classifications. That is exactly the supplementary behavioral context an agent needs before committing a paid call.

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-loaded with the usage cue and risk, then inputs and cost — a logical order with little waste. The '(real money)' note on the default network is repeated verbatim from the schema, a minor redundancy, but overall it is tight for the amount of information conveyed.

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 compensates by describing what comes back (address classification plus per-type key facts). Combined with inputs, cost, and the pre-call safety warning, nothing an agent needs to invoke this 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?

Schema description coverage is 100% and both parameters are documented, so the schema already carries the load. The description largely restates the schema ('address: Any Solana address', 'network (optional): Which Solana network... default mainnet-beta') without adding format or syntax detail beyond it, 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 — 'Says what any address is' — and enumerates the outputs (wallet, token account, token, program, stake account) with 'key facts for each'. This clearly distinguishes it from siblings like find_token, token_account, and wallet, which each cover narrower address categories.

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 says when to run it: 'when you're not sure what an address is, before sending to it or passing it to another tool', backed by the concrete consequence that SOL sent to a token or program address can be stuck for good. It doesn't name a specific alternative sibling to use instead, but the trigger condition and preconditions are unambiguous.

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