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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, yet the description still adds value: the chat-pass branch only works with a credential, and it explains the meaning and current OFF state of the `prices.abuso_24h_usd` door. That is meaningful behavioral context beyond the structured fields.

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?

Four compact sentences, front-loaded with the core purpose ('Preços e tetos') and then the usage rule. It is efficient, though the internal jargon ('porta de UA vazio/curl') costs some clarity for an external reader.

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 zero-param, read-only tool with no output schema, the description covers enough of the return surface (current prices, caps, credential-dependent chat-pass status, and a specific field) to invoke it meaningfully. It does not fully enumerate the response shape, but the complexity is low.

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 tool takes zero parameters, so per the rubric the baseline is 4 and there is no parameter semantics to compensate for. Nothing in the description contradicts or embellishes a parameter contract.

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 states a specific resource (current prices and caps) and even names a field (`prices.abuso_24h_usd`), so an agent can tell this tool returns live billing numbers. However, it never distinguishes itself from the sibling `pricing` tool, leaving a real ambiguity about which one to pick.

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?

It gives a clear directive: read the current number from here before spending a call rather than assuming the documented price. That is actionable when-to-use guidance, but it never names an alternative sibling (e.g. `pricing` or `chat_pass`) or states 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.