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

Annotations already carry readOnlyHint and openWorldHint, so the safety profile is covered. The description still adds useful context by scoping the content to "public" articles and enumerating the returned fields, though it says nothing about rate limits, auth, or failure behavior for non-canonical URLs.

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 sentences, zero filler, and the directive sentence (what it fetches and from what) leads before the routing sentence. Every clause earns its place.

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 a single-parameter read tool with an output schema and read-only/open-world annotations, nothing an agent needs is missing: input format is stated, the payload is summarized, and sibling tools are routed. Return-value detail is legitimately delegated to the output 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?

With one parameter at 100% schema description coverage, the schema already documents `url` as the "Canonical i article URL". The description's phrase "from a canonical `url`" reinforces the requirement but adds no format or constraint detail beyond the schema, 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?

Specific verb ("Fetch") plus a precise resource ("public i article") with an enumerated payload (headline, section, authors, times, lead image, body paragraphs). It distinguishes itself from the sibling list tools by naming them directly, so an agent can separate article-fetch from feed/browse without opening a schema.

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 routes the agent explicitly: inews_headlines for story lists, inews_sections to browse sections, inews_news for the general feed. That covers alternatives clearly, but it never states the positive trigger ("use this once you have a canonical article URL") and gives no exclusion rules, so it stops short of the full when/when-not pattern.

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