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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds useful boundary context that the input must be a canonical /article/ URL and that non-article page types will not work, but says nothing about auth or pagination beyond that.

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 tight sentences, front-loaded with the core action and URL constraint, followed by sibling routing. No filler and nothing redundant.

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?

Output schema exists so return values need not be restated, yet the description still summarizes the payload (metadata and body paragraphs). For a single-param fetch tool, all the routing and boundary context an agent needs is present.

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% and the only parameter (url) is documented. The description nevertheless adds meaning beyond the schema by specifying the canonical /article/ path and excluding video/gallery/live URLs, tightening what a valid value looks like.

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 (Fetch) and resource (CTV News story metadata and body paragraphs), and explicitly carves out what is not an article page (video, photo-gallery, live-stream). An agent can distinguish it from sibling headline/author tools 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?

Explicitly routes to alternatives: ctvnews_headlines to find stories, ctvnews_author for a writer profile. It also states exclusions (video, gallery, live-stream pages are not articles), giving both when-to-use and when-not-to-use guidance.

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