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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered. The description adds one genuine behavioral trait — 'Never invents missing fields' — which tells the agent how to interpret absent data. It stops short of disclosing caching (max_age_ms) or response_mode behavior.

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 short sentences, front-loaded with the core action and followed by the key behavioral constraint. No filler and nothing buried.

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 values need not be explained, but for a 4-parameter tool with zero schema descriptions the absence of any parameter guidance (TTL, response mode, field selection) leaves the agent under-equipped to invoke it correctly.

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 0%, so the description carries the full burden, yet it only vaguely gestures at `select` ('selected product fields') and says nothing about max_age_ms (a cache TTL) or the minimal/standard/evidence response_mode. Two of four parameters are entirely undocumented anywhere.

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?

Specific verb (extract) plus resource (selected product fields) and scope (public product page), clearly distinguishing it from generic scraping or QA tools. It does not, however, name or contrast against any sibling such as compare_products or source_snapshot, so routing relies on the agent's own inference.

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 phrase 'public product page' implies a usage context, but there is no explicit when-to-use versus the siblings (compare_products, web_qa, source_snapshot) and no exclusions or prerequisites stated.

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