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

With no annotations provided, the description carries the full burden. It discloses a confirmation requirement before execution, clarifies that account_fk is a database ID not an address and may not be 0, and notes that it returns a JSON object. These are meaningful behavioral details beyond the schema, though it does not elaborate on side effects like balance deduction or failure conditions.

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 main description 'Purchases a digital asset from the account's FIAT balance' is repeated verbatim twice, and the confirmation note is awkwardly embedded in the first sentence. The @param block is standard but the redundancy wastes space and reduces clarity.

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 financial mutation with no annotations, the description provides the core action and confirmation requirement but omits prerequisites (e.g., sufficient FIAT balance), error/edge cases, and fee implications. The output schema exists, so return details are not needed, but the overall operational context is thin.

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 description coverage is 0%, so the description must compensate. It does document all four parameters, including a valuable clarification for account_fk (database ID, not address, cannot be 0). However, descriptions are brief and lack specifics such as where to obtain digital_asset_fk or the format of api_key. The compensation is partial.

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 'Purchases a digital asset from the account's FIAT balance' with a specific verb and resource, and it is distinguishable from sibling tools like account_sell, account_swap, and account_buy_telco. The purpose is unambiguous.

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 provides clear context for the tool's intended use (buying digital assets with fiat) and includes an explicit procedural instruction 'Confirm (yes/no) before executing'. However, it does not mention alternatives or when not to use this tool, making it contextually clear but lacking exclusions.

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