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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint/openWorldHint, so the safety profile is covered. The description adds real context beyond them: it reads directly from chain via RPC multicall and returns both raw (wei) and formatted balances, which clarifies cost/behavior.

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?

Three sentences, each earning its place: purpose, mechanism, prerequisite usage, then return format. Front-loaded with the core operation and free of 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?

An output schema exists, so return values need not be explained, yet the description still summarizes the raw/formatted shape. Combined with complete annotations and schema, an agent has everything needed to call it correctly.

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% (chain_id lists valid chains, wallet_address and token_addresses documented), so the schema already carries parameter meaning. The description adds no syntax or format detail beyond the schema, making the baseline 3 appropriate.

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 ('Get native ETH and ERC20 token balances for a wallet address'), covering both native and ERC20 scope. An agent can readily distinguish it from siblings like read_wallet_allowances (allowances, not balances) even though no sibling is named explicitly.

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?

Provides explicit when-to-use guidance by naming the write tools it should precede (write_account_add_liquidity, write_account_deposit) and the rationale (verify sufficient tokens). No when-not-to-use or explicit alternative reference, but the positive routing is strong.

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