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

With no annotations, the description carries the full burden and usefully discloses both the cost ('Pay-per-call ($0.005 USDC)') and the return contents (native balance + live USD value). It does not mention error handling or the price source, but for a simple read operation this is adequate.

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?

The description is a single sentence with zero wasted words. It front-loads the core purpose before the cost detail, and every phrase ('Native balance', 'live USD value', 'any polygon address', 'pay-per-call') adds necessary information.

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 one-parameter read tool with no output schema and no annotations, the description covers the essentials: what it returns, for which addresses, and at what cost. Minor gaps like address validity requirements or currency code (USD vs USDC) are non-critical for basic selection and invocation.

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?

The input schema already describes the address parameter with 100% coverage ('polygon address (0x...)'). The description adds no parameter-specific meaning beyond what the schema provides, so the baseline score of 3 applies.

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 states a specific verb and resource: 'Native balance + live USD value' for 'any polygon address'. It clearly differentiates from siblings like base_balance by specifying the Polygon network and from polygon_token/polygon_stables by noting 'Native balance'.

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 phrase 'for any polygon address' provides clear context for when this tool applies. It does not explicitly name alternatives or exclusions, but the scope is unambiguous and the network/asset type is self-evident from the wording.

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