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

readOnlyHint and openWorldHint already declare this is a safe, open-web read, so the description only needs to add context. It contributes that the fetch is single-article and returns both content and metadata, but says nothing about failure modes, paywalls, or response shape. Useful but thin given annotations carry the safety profile.

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 short sentences with zero filler; the tool's action and scope come first and the alternative-tool pointer follows. Nothing needs trimming.

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-input fetch tool, the description, a fully documented schema, safety annotations, and an output schema together cover everything needed to invoke it correctly. No essential agent-facing information is missing.

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?

There is one parameter and the schema documents it fully at 100% coverage, including the required canonical URL format. The description adds nothing beyond what the schema already says, which is the expected baseline when the schema does the work.

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') plus resource ('published content and metadata') and scope ('one Yahoo News article URL'). It also names the sibling it is not (yahoo_news_category), so an agent can distinguish it without opening any 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 browsing behavior to yahoo_news_category, making the when-vs-alternative choice clear. It doesn't state the inverse condition (that this tool requires an already-known article URL) or distinguish it from other article-adjacent siblings like yahoo_news_related, but the key routing is present.

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