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

Annotations already declare readOnlyHint and openWorldHint, so the description adds real value by disclosing that the site serves the full body to anonymous readers even when is_gated marks its content tier — non-obvious behavior an agent could otherwise misinterpret. It omits auth, rate-limit, or failure behavior, so it is not exhaustive.

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 tight sentences, front-loaded with the core action and immediately followed by the key gating caveat and the sibling routing. Every sentence earns its place with no redundancy.

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?

An output schema exists, so return values need not be explained; the single required parameter is fully covered. The description adds the one non-obvious behavioral caveat (gated content still returned), making it complete for this simple one-param fetch tool.

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?

Only one parameter and schema description coverage is 100%, so the schema already documents url. The description reinforces 'canonical url', which adds some emphasis but no syntax or format detail beyond what the schema provides — the 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 (Foreign Policy article metadata and body paragraphs) tied to a canonical url. It clearly distinguishes itself from the sibling tools it names, so an agent can tell it apart from foreignpolicy_headlines and foreignpolicy_author 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 the agent: 'Use foreignpolicy_headlines to find articles or foreignpolicy_author for a profile.' That gives clear alternative-selection context, though it does not state an explicit exclusion (e.g. when not to fetch, such as already having the full text).

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