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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description goes beyond them by disclosing the payment model — $0.05 USDC per successful call via x402 when no API key is present. That is material pre-call cost information an agent could not get from the annotations, though rate limits and failure/latency behavior are not covered.

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 sentences, no filler: the return payload is front-loaded, then the pricing/auth condition. Every clause carries information the agent needs.

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 listing the returned fields, and it covers the cost/auth path. What remains unstated is edge behavior — e.g. results for an unknown .sol name or an address with no transactions — which slightly limits completeness.

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 description coverage (base58 32-44 chars or .sol name). The description repeats that same duality ('Solana address or .sol name') without adding format or validation detail, so the schema does the work and 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 states a specific resource (Solana address or .sol name) and enumerates exactly what is returned: SOL balance in SOL and USD, account type, SPL token holdings, recent transactions. This distinguishes it cleanly from chain-specific siblings such as eth_address, btc_address and tron_address without the agent needing to open a schema.

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 scoping phrase 'for a Solana address or .sol name' tells the agent precisely when this tool rather than the Ethereum/Bitcoin/Tron siblings applies. It does not state explicit exclusions (e.g. what to do for non-Solana input), so it stops short of a full when/when-not treatment.

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