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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it returns a URL plus current balance, and it explicitly forbids in-chat payment or card handling. It does not describe link expiry, session binding, or what the returned page looks like, so it stops short of rich disclosure.

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?

Two sentences, front-loaded with what is returned, followed by the constraint on agent behavior. No filler or redundant restatement of the title.

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 single-parameter, no-output-schema tool with annotations present, the description covers purpose, return content (link plus balance), and the key safety constraint. Minor gaps such as link lifetime or whether the balance is fetched live are not addressed but are unlikely to block correct invocation.

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?

Only one optional parameter (language) exists and schema description coverage is 100%, so the schema already explains the BCP-47 tag and that replies and prices follow it. The description adds no parameter-level meaning beyond the schema, which is the expected baseline here.

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?

States a specific verb and resource: returns the avatar.diatech.solutions top-up page and the user's current balance, with payment methods (card/PIX) and currency (BRL) named. It is clearly distinguishable from a pure balance-read tool like get_balance, though it does not explicitly name a sibling to contrast with.

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?

Gives concrete operating instructions: show the link and let the user pay on the site, because no payment happens in chat and card data must never be handled. It does not spell out an explicit when-not or name an alternative tool, but the usage context is unambiguous.

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