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

Annotations already declare readOnlyHint and openWorldHint, yet the description adds real value beyond them: 'Free' discloses cost, 'live at the latest block' discloses freshness/no-caching semantics, and it names exactly which assets come back. It stays silent on error behavior for malformed addresses and on rate limits, which keeps it off a 5.

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?

Dense and front-loaded: cost, read-only nature, returned assets, chain scope and freshness all land in one sentence before the address note. The trailing address clause is truncated, leaving a ragged end that slightly undercuts an otherwise efficient structure.

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 two-parameter read tool with no output schema, the description covers what is returned (native coin plus one stablecoin), which chains, and how fresh the data is. It does not describe the response shape (numeric format, presence of both assets when zero), which is the remaining gap.

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% and the chain default plus enum are fully documented in the schema, so the description's chain list and address-format note largely restate structured data. The address hint is cut off mid-token ('Tron T...'), adding no usable detail beyond what the schema already provides.

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 (native coin + USDC/USDT balance), a precise scope (one address, one chain) and enumerates the supported chains. The 'one chain' framing also implicitly separates it from the multichain sibling, so an agent can pick between them without opening a schema.

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 scoping phrase 'of one address on one chain' plus 'Free, read-only' gives clear selection context and steers multi-chain queries elsewhere. It never names the alternative sibling or states exclusions explicitly, so the routing is inferred rather than spelled out.

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