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

Annotations already declare the safety profile (readOnlyHint, idempotentHint, non-destructive), so the bar is lowered, yet the description adds real behavioral detail: the auth requirement and its source, plus the exact error object shape (error.code, error.message, error.http_status, error.retry_recommended, error.retry_after_seconds). That error contract is genuinely valuable for retry logic and goes well beyond the annotations.

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?

Three front-loaded sentences: purpose first, auth second, error behavior third, with no filler. The error-field enumeration is long but each field is load-bearing for an agent handling failures.

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?

An output schema exists, so return-value shape needn't be explained, and the description covers the auth prerequisite and failure contract. For a simple paginated read tool this is close to complete, with only the sibling-routing guidance missing.

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%, so the schema already documents limit (default 50, max 200), offset, and the api_key format. The description only restates the api_key format hint (pwk_live_...) with no additional semantics, so the baseline 3 for a fully-covered schema applies.

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 ('List products your account watches') with a scope qualifier ('for continuous price updates') that distinguishes it from a general product listing. It does not explicitly contrast with the nearby sibling list_price_alerts, so an agent must infer the product-vs-alert distinction, but the purpose is unambiguous.

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?

The description states a prerequisite (a Pricewatcha API key, with a URL for obtaining it) which is useful context, but it gives no guidance on when to choose this tool over siblings like list_price_alerts, get_watch_status, or get_product. Usage is only implied by the name.

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