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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses the cost model ($0.002 USDC per successful call via x402 on Base, Solana, or Arc), that failed calls are free, paywall limitations, and a technical dependency on <article>/<main> markup. These are material operational details an agent needs before invoking a paid external fetch.

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 sentences, each dense with useful information: first defines scope and output, second states read/paywall constraints, third covers pricing and billing edge cases. No sentence is redundant, and the core purpose is front-loaded.

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 exists (so return fields need not be described in depth) and annotations cover safety, the description fills in the remaining critical gaps: cost, failure billing, paywall behavior, and extraction dependency on semantic HTML. An agent has enough to call this correctly and understand the transactional risk.

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 100%, with both url and maxChars fully documented in the input schema, including the default (8000) and range (500–40000). The description does not add syntax or format detail beyond what the schema already provides, so the baseline of 3 is correct.

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 states a precise verb and resource: 'Extracts one article from a public news or blog page,' and enumerates exactly which fields are returned (headline, author, times, description, Markdown body). It also distinguishes itself from the many 'search_*_articles' siblings by clarifying 'Reads the page you name only,' so an agent can tell it is an extractor, not a search tool.

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?

Usage conditions are clear: it works on a single named public article page, paywalled text is excluded, and body extraction depends on <article> or <main>. However, it does not explicitly name sibling alternatives (e.g., 'use search_bbc_news_articles to find articles first'), leaving the broader tool-selection context implied rather than stated.

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