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

Annotations already cover read-only/idempotent safety, and the description adds substantial context beyond them: pricing is sourced on-chain from Uniswap v3 pools on Base, both chains are valued in one call, tokens that cannot be priced are returned separately, cost is 0.003 USDC per call, and p95 latency is 5000 ms. Cost and latency disclosure is exactly the kind of operational detail annotations cannot carry.

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 use-when clause and the exclusions before the return/cost details, which is the right ordering. The middle sentence is long and crams return shape, pricing source, per-chain totals, unpriced tokens, cost and latency into one breath, costing some readability.

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?

An output schema exists, so return values need no explanation, yet the description still orients the agent on what comes back. Combined with cost, latency, chain scope, and pricing methodology, an agent has everything needed to decide and invoke correctly for a 3-parameter 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 description coverage is 100%, so address, chains (enum, default both chains) and response_format are fully documented in the schema; the baseline is 3. The description only loosely gestures at chains ('on Ethereum and Base in one call') and says nothing about response_format, so it adds no meaning beyond the schema.

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 resource and outcome: a wallet's portfolio value in USD, net worth, or token balances with USD value for a 0x address, plus scope constraints (Ethereum and Base). It differentiates by exclusion (no Solana, tx history, NFTs, DeFi positions, long-tail tokens) but never names the overlapping siblings blackwood_wallet_balances or blackwood_wallet_portfolio, so the agent must infer the boundary.

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?

Explicit 'Use when you need...' plus a concrete 'Do not use for...' exclusion list gives clear when/when-not guidance. What is missing is a positive pointer to the correct alternative tool (e.g. wallet_balances for non-priced balances, token_price for long-tail tokens), so routing between siblings is still partly inferred.

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