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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so the safe-read profile is covered by structured data. The description adds some behavioral value by describing the returned payload and the negative case ("or says there is none"), plus the Portuguese-language output note, though return details are largely duplicated by the output schema.

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 tightly written sentences with zero filler, front-loaded with the core question before describing the return payload. Every clause earns its place and nothing is repeated.

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?

With a full input schema, output schema and safety annotations, the description covers what the tool does, what it returns, and the no-result case adequately for a single-parameter read tool. The only shortfall is the absence of guidance on when to prefer sibling tools.

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 100% for the single url parameter, so the schema already carries the semantics. The description's phrase "product page URL from an online store" largely restates the schema rather than adding format or validation nuance (e.g., must be a specific store's product page, not a category or redirect URL).

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 gives a specific verb+resource ("check whether ... has an active deal for a product page URL"), which is clear and actionable. It implicitly distinguishes itself from ID-based siblings like get_product and get_deal by keying on a store URL, but it never names or contrasts those siblings explicitly, so it stops short of the top score.

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?

Usage is only implied: the agent can infer you call this when you have a product page URL and want to know if a deal exists. There is no explicit when-to-use vs. when-not, no statement of prerequisites, and no routing to alternatives such as get_product or get_deal when a URL is not available.

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