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

Annotations already declare readOnlyHint and openWorldHint, and the description goes further by disclosing the free-tier rate limit (30 calls/day per client) and the no-JS-rendering limitation, both of which materially affect invocation decisions. It stays silent on failure/empty-extraction behavior, which keeps it out of the top score.

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 short sentences, front-loaded with the core action and tightly packed with the mode list, rate limit and rendering constraint. No sentence is wasted.

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 an 11-parameter tool with no output schema and only 64% schema documentation, the description covers the essentials but leaves gaps: several extraction modes (table, events, price, json) are named without clarifying their behavior, and the paid/x402 path is not explained beyond what the schema says.

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 coverage is 64% and the schema already documents the enum values, selector requirements, match, jsonpath and paid behavior. The description's mode list largely restates the enum and adds nothing about all, sameHost, tableIndex, or how fields/tableIndex interact. Baseline 3 is appropriate.

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 gives a specific verb ('fetch') and resource ('one public static web page') plus the extraction outcome, and the word 'static' plus the enumerated modes signals a one-shot scrape. It does not explicitly name watch_page, which is the closest sibling, so differentiation from it is left to the agent.

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?

It states useful operating constraints ('no JavaScript rendering', 30 free calls/day) that imply when this tool fits, but never says when to prefer watch_page or get_changes instead, nor what to do when the page requires JS.

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