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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds substantive context beyond them: all amounts are normalized to USDT TRC20 accounting regardless of the payer's coin, and each balance is returned both as a decimal string and in atomic units. No output schema exists, so explaining the two buckets and their meaning ('held' = reserved by payouts in progress) is doing real work.

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?

A single compact sentence pair, front-loaded with the verb and result, then the accounting rule, then the two bucket definitions. The parentheticals are dense but each one carries semantics an agent needs; nothing is redundant 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?

With zero parameters, full annotation coverage, and no output schema, the description is exactly the right place to define return shape, and it does: two balance categories with definitions plus dual numeric representations. An agent has everything needed to call and interpret the result.

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 tool takes zero parameters, so there is nothing for the description to clarify and the baseline of 4 applies. No wasted text is spent restating an empty schema.

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 ('Returns the account balance') and immediately scopes it to the two balance categories (available, held). This is unmistakably distinct from siblings like get_account or list_transactions, so an agent can select it without opening the 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?

Usage is only implied: the mention that 'available' can be paid out or converted now hints at pre-payout/pre-conversion checks, and 'held' being reserved by in-progress payouts signals reconciliation use. There is no explicit when-to-use statement or named alternative, which is a real gap even for a zero-param read.

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