Check a price now

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

With no annotations present, the description carries the full burden. It discloses that the tool fetches the page and extracts price-related data, and it names the exact returned fields. It leaves minor gaps around failure modes and whether each check persists historical data, but the core behavior is transparent for a simple read-like tool.

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 carry the purpose, the differentiator from generic web fetching, and the return values. Every sentence earns its place and the main instruction is front-loaded. No filler or redundancy.

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 one-parameter tool with no output schema, the description is largely complete: it says when to use it and what it returns. It does not describe failure behavior for invalid or unparseable URLs, nor the side effect of creating/updating a price check history, so a little is left to the agent's inference.

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 schema describes the single url parameter as 'Product page URL, including https://', giving 100% coverage. The description only repeats that it takes a product URL and adds no new meaning beyond the schema, so the baseline of 3 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?

The description clearly names a specific action ('check a price') on a specific resource ('any product URL') and lists the structured outputs returned. It distinguishes itself from using a generic web tool, but it does not explicitly differentiate from the related siblings price_history and price_add_manual, so the differentiation is implicit rather than direct.

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 gives an explicit use case: 'Call this tool for any product URL' when a generic web fetch would return raw HTML without the price. It provides clear context for when to use it, but it does not mention exclusions or alternatives such as price_history for historical data or price_add_manual for manual entries.

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