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

With no annotations, the description itself must indicate behavioral traits. It communicates that the tool is a read-only lookup ('Return the current USD balance') and that it is useful for checking funds before ordering. It does not disclose error behavior, token validation, or what the returned payload looks like, so it covers the basics without being rich.

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 short sentences front-load the core behavior and then give a decision rule. There is no filler or repetition, and every sentence adds value.

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 simple single-parameter tool, the description provides the essential purpose and a clear usage context, and the sibling list supports routing. It does not describe the return format or failure cases, and there is no output schema to compensate, so it is slightly incomplete but still adequate for typical use.

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 schema has 0% description coverage, and the tool description does not explain the account_token parameter beyond the phrase 'for an account'. The token name is somewhat self-explanatory, but the agent is not told what the token represents, where to obtain it, or how it is used, which is a meaningful gap for a required parameter.

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: it returns the current USD balance for an account. It also frames this against related actions (create_order, topup_create), making the tool's purpose immediately clear and distinct from the listed siblings.

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?

It explicitly says when to use this tool: to decide whether to call create_order or topup_create first. This gives the agent a concrete decision rule and mentions the relevant alternatives by name.

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