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

With no annotations, the description carries the full burden. It discloses the need for PIN and the confirmation step, but it is ambiguous whether 'Confirm (yes/no) before executing' is a tool behavior or an instruction to the agent. It lacks details on side effects, reversibility, or error conditions, which is important for a financial mutation.

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 repeats 'Charges the account based on a presented QR-code or NFC card' twice in the opening, which is redundant. The @param block is structured and efficient, but the duplicated opening wastes space and could confuse. Not terrible, but not clean.

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 description covers purpose, prerequisites, parameter meanings, and states '@return: a json object'. However, it does not explain what the JSON contains, error cases, or idempotency. The ambiguous confirmation step and lack of edge-case context leave gaps for a financial transaction tool with no annotation support.

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 input schema has 0% description coverage, but the description compensates fully with detailed @param explanations. It clarifies that account_fk is a database ID (not an address) and may not be 0, describes token as the wallet_api_token from /access/login, and specifies that pin belongs to the account_address being charged. All 7 parameters receive meaningful semantic annotation.

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's function: 'Charges the account based on a presented QR-code or NFC card.' This is a specific verb ('Charges') and resource ('the account') with a distinguishing mechanism (QR-code/NFC card). It differentiates from siblings like account_send or account_pay by the presentation method.

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?

Provides explicit guidance: 'Confirm (yes/no) before executing' instructs the agent to seek user confirmation, and 'The payer must present a valid PIN' sets a required prerequisite. While it doesn't explicitly mention alternatives or exclusions, the context of QR/NFC charging and the PIN requirement offer clear usage boundaries.

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