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

Beyond the readOnly/openWorld/idempotent annotations, the description discloses real operational behavior: null means unknown rather than zero, one admitted call consumes one shared account request even on error, and there are no automatic retries. That quota and retry disclosure is exactly the kind of trait annotations cannot express.

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 short, front-loaded sentences with no padding. The one weak spot is 'Product guides do not filter condition, language or edition', which is cryptic in context and its relevance to a single-variant price read is not self-evident.

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 an output schema present, the description need not detail returns, yet it still clarifies return semantics (null-vs-zero) and call-cost behavior. The main gap is the undocumented 'view' parameter, which the agent has no guidance on.

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 coverage is 50%: card_id is fully documented in the schema, but the 'view' enum (compact/full) is undocumented in both places and the description never explains the difference. The phrase 'one exact variant' reinforces card_id semantics but adds nothing for the unexplained view parameter, so this sits at the baseline.

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 ('Read measured EUR prices') plus a scope qualifier ('for one exact variant'), which is enough to separate it from aggregate siblings like batch_prices. However it never names the closely related get_card_prices or get_price_history, so the agent must infer the distinction between 'current price' and 'price history' itself.

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 explicit when-to-use or when-not-to-use guidance and no named alternative, despite four adjacent price tools in the sibling list. 'One exact variant' only weakly implies 'do not use this for multiple cards', leaving the routing decision to inference.

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