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

The annotations already establish read-only, idempotent, non-destructive behavior. The description adds useful context on top by noting the data is 'real-time' and by specifying which balance fields are returned. There is no contradiction with the annotations.

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 compact: two informative sentences plus a call example. The core behavior and return fields are front-loaded, and every part contributes to understanding what the tool does and how to invoke it.

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 read-only tool with two required parameters, a rich output schema, and full annotations, the description is complete. It states the main behavior, return categories, scope, and gives an invocation example, so an agent has what it needs to call the tool 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% and both parameters already have descriptive meaning: the API key format 'client_id:secret' and the Plaid access token. The description's example reinforces these formats but adds no substantial semantic detail beyond the 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?

The description opens with a specific verb and resource ('Get real-time account balances') and identifies the scope as 'linked accounts.' It also enumerates the returned balance types (current, available, limit), making it easy to distinguish from sibling tools like get_accounts and get_transactions.

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 use case is implied by the phrase 'Get real-time account balances,' but there is no explicit guidance about when to prefer this tool over get_accounts or get_transactions, and no when-not-to-use conditions are stated.

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