get_balance

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

The readOnlyHint annotation already declares this as a safe read operation. The description adds context about the specific balance components (available, blocked, automatically invested) and that it returns the current balance, which enriches behavioral understanding without contradicting the annotation.

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 concise and well-structured with an opening sentence, Args list, and Returns section. It is front-loaded with the primary purpose. The Args/Returns format adds a bit of verbosity but remains efficient and scannable.

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?

The tool is simple with three parameters and an output schema. The description covers purpose, parameters, and return value adequately. The mention of account_id linkage to list_accounts adds the necessary context for the interaction flow.

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 provides no descriptions (0% coverage), so the description carries the full burden. It clearly explains each parameter: subject_id as CPF, bank as identifier, and account_id as returned by list_accounts, adding meaning beyond the raw 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 clearly states the tool returns the available, blocked, and automatically invested balance of a specific bank account. It uses a specific verb ('Returns') and resource ('balance'), distinguishing it from sibling tools like list_accounts and list_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 description implies a workflow by noting that account_id is returned by list_accounts, which guides when to use this tool. However, it does not explicitly mention when not to use it or alternatives beyond that hint.

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