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

Annotations already declare destructiveHint, idempotentHint, and readOnlyHint, so the description does not need to repeat those. It adds meaningful behavioral context: the SQL owner guard prevents cross-agent top-ups, and 'Never Stars' imposes a strict currency limitation. This goes beyond what annotations provide, though it does not explain idempotency or destructive effects.

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 short and has no filler, but the first sentence is grammatically awkward and ambiguous ('from this agent 2401 USDT'). It front-loads the endpoint and core constraint, yet the lack of clarity in key phrasing reduces effectiveness.

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 destructive, idempotent write operation with no output schema, the description should clarify the effect, return behavior, idempotency semantics, and parameter meanings. It provides only ownership and currency constraints, leaving important operational details undocumented.

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, but it only restates that ext_id is required and that card_id must belong to the same agent. It does not explain the meaning of amount, the role of ext_id (likely an idempotency key), or how the '2401 USDT' phrase relates to the amount 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 identifies the operation as topping up a card via the named endpoint and adds specific constraints: the card must belong to the agent and the currency is USDT, not Stars. It is not a tautology and the core action is clear, though the phrase 'from this agent 2401 USDT' is cryptic and could confuse the amount or agent meaning.

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?

There is no guidance on when to use this tool versus alternatives like create_card or get_card_details. The description only states constraints ('card_id must belong to the same agent', 'Never Stars') rather than explaining the selecting context or when not to use it.

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