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

Goes well beyond the annotations: live mainnet read, partial-failure behavior (tokens is null with a note when the public node does not serve accounts), 400 uncharged for invalid addresses, and explicit pricing/free-tier and per-call charging semantics. The 'each call is charged, so repeats are not free' line even explains why idempotentHint is false.

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 purpose, then error, example, pricing, and safety in descending order of importance. The pricing sentence is dense (x402, card key, free tier, failed calls) but every clause is decision-relevant; nothing is redundant filler.

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 carries the return-value burden and does so: lamports and SOL, per-token fields (mint, symbol, decimals, amount), and the null-with-note degradation case. Error behavior, cost, and side-effect profile are all covered for a one-parameter read tool.

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 already 100% for a single parameter, yet the description still adds the 32-byte base58 validity rule and a concrete example address. That is genuine meaning beyond the schema's bare 'Solana wallet address (base58)'.

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 ('SOL balance of a Solana wallet, read live from mainnet') and enumerates what is returned (lamports, SOL, SPL token accounts). The 'Solana' qualifier plus the SPL token mention separates it cleanly from the many EVM *_balance siblings.

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?

'Use to check a Solana wallet before a payment' gives a concrete usage context. It stops short of exclusions or naming alternatives such as solana_token for a single-token lookup, so an agent still has to infer when to prefer a sibling.

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