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 genuinely useful behavior: incomplete, truncated, challenged, or contaminated upstream pages return an error rather than partial text, which tells the agent to expect hard failure, not degraded content. Auth and rate-limit behavior are not mentioned, keeping it below a 5.

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 earning its place: purpose+scope first, failure mode second, sibling routing third. Front-loaded and free of filler.

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?

With an output schema present, return values need not be explained. Purpose, error behavior, and alternative-tool routing together cover everything an agent needs to select and invoke this tool correctly.

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 single param already carries the description 'Canonical Foreign Affairs article URL'. The description's 'canonical url' phrasing largely restates the schema rather than adding syntax, format, or validation detail. 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?

States a specific verb ('Fetch') and resource ('public Foreign Affairs article metadata and ordered body paragraphs') keyed to a canonical url. It is immediately distinguishable from the sibling list/topic/profile tools. No ambiguity about what is returned.

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 the agent to three named alternatives with the condition that selects each: foreignaffairs_headlines for story lists, foreignaffairs_topic for a topic, foreignaffairs_author for a profile. This is exactly the when-to-use-this-vs-alternatives guidance the dimension asks for.

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