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

Annotations cover the safety profile (readOnly, openWorld, non-destructive), and the description adds substantial behavior beyond them: parallel fetching, per-page failure explanations, robots.txt compliance, and the cost/rate model (US$0.01 per call, 3 free calls/day). Cost and quota are exactly the operational facts an agent needs before invoking a paid, metered 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?

Effectively one dense sentence with semicolons that front-loads the core capability, batch size, and return shape before moving to cost and pairing advice. Every clause carries information, though the packed semicolon chain is slightly harder to scan than distinct sentences.

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?

Given an output schema already exists, the description need not explain return values, yet it does name the returned fields. Combined with batch limits, error reporting, robots.txt, and pricing, an agent has everything required to call this correctly and budget for it.

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% – both `urls` (1-10 https URLs) and `max_chars` (default 6000) are documented in the schema. The description reinforces the 1-10 URL bound but adds no new semantics such as URL format rules or truncation behavior, 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?

States a specific verb (read/fetch) and resource (web pages) with the shape of the output (title, description, main text, links) and the batch limit. It is immediately distinguishable from the sibling web_search, which returns URLs rather than page content.

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?

Explicitly says the tool pairs with web search and that callers should pass the URLs it returned, which is a concrete when-to-use rule tied to a named sibling. It stops short of stating exclusions (e.g. when to prefer web_search or a browser tool instead), so it is clear context but not a full decision rule.

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