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

Annotations already declare readOnly, idempotent, openWorld. Beyond that, the description discloses meaningful behavior: results are 'source-backed', values are not invented, and missing data is explicitly reported alongside differences. It does not cover caching behavior (max_age_ms) or rate/auth constraints, so it is not fully comprehensive.

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 dense sentences, zero filler, with the operation and its output contract front-loaded. Every clause carries information (scope, boundedness, provenance, missing-data handling, no-fabrication guarantee).

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 detail is rightly omitted, and the read-only annotations cover safety. However, with 4 parameters at 0% schema coverage and no usage routing, the definition leaves an agent unable to select values for response_mode, max_age_ms, or select without opening the schema.

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% for 4 parameters, so the description carries the full burden — and it does not. 'Source-backed fields' loosely gestures at select and 'bounded call' at maxItems/max_age_ms, but response_mode, max_age_ms, and the selectable field enum are never explained. The vague hints do not compensate for the coverage gap.

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: 'Compare multiple public product pages in one bounded call.' The scope word 'public' and the bounded-call framing make the operation concrete. It stops short of explicitly differentiating itself from siblings like web_to_product (single-page extraction) or website_audit.

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?

No when-to-use or when-not-to-use guidance is given, and no alternative sibling is named. The phrase 'in one bounded call' only implies a cost/efficiency motivation for choosing this over repeated single-page calls. An agent must infer routing from the name alone.

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