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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the read-only nature is covered. The description adds valuable behavioral context: it performs direct contract calls on the chosen EVM chain, prices via DefiLlama, works for any token (no whitelist), and discloses cost ($0.002 per call, 10 free/day). This exceeds annotation coverage without contradicting it.

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 front-load the outputs and wallet balance, then explain the mechanism and pricing. Every sentence earns its place; no fluff. The structure is efficient, though pricing details are placed secondarily rather than in a dedicated section. Still appropriately concise.

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?

For a read-only tool with 3 parameters and no output schema, the description covers purpose, method, scope, and cost. It does not specify return format (e.g., decimals vs raw balance) or potential errors, but these are minor given the clear list of outputs. Annotations cover safety, so the overall context is sufficient.

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 67%: token has no description (only pattern), chain has enum description, wallet says 'optional holder'. The description clarifies that the wallet parameter provides a balance, and that chain determines the EVM network, but it does not elaborate on token semantics beyond the pattern. It adds some value but leaves token meaning implicit.

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 clearly states it reads name, symbol, decimals, total supply, USD price, and optional wallet balance of any ERC-20 token. It specifies the verb 'read' and the resource, and lists the exact fields. This distinguishes it from siblings like crypto_price (price only) and wallet_holdings (all holdings), making its purpose unmistakable.

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 description notes it works for any token, listed or not, and that it reads on chain with direct contract calls. However, it does not explicitly contrast with alternatives like crypto_price or wallet_holdings, nor does it state when NOT to use it. The context is clear but exclusionary guidance is absent.

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