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

Despite annotations declaring readOnlyHint=false, the description preemptively explains why ('Reads or computes only; not marked read-only because each call is charged'), removing a potential contradiction. It also discloses pricing, free tier, and failure behavior, plus the return shape.

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 core purpose, then use cases, then billing/behavioral note. All sentences earn their place, though the pricing detail makes it slightly dense for a simple lookup.

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 exactly what is returned. Combined with the safety rationale and billing model, 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 coverage is 100%, so the baseline is 3. The description goes further by clarifying the owner/token/spender relationship (a wallet's token a spender contract is approved to move), adding semantic context to what the fields mean.

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 (check allowance) plus resource (ERC-20 approval on Base) and even enumerates the exact return contents (raw/formatted allowance, symbol, decimals, unlimited flag). This clearly distinguishes it from siblings like base_token_balance or base_token_info.

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?

Gives two concrete use scenarios: pre-swap/deposit approve checks and auditing for risky unlimited approvals. It does not explicitly name an alternative sibling, but the guidance is clear enough for selection.

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