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

Annotations already declare readOnlyHint and openWorldHint. The description adds real behavioral context beyond them: only public metadata and body paragraphs are returned, and access-limited articles may not expose full text. Return shape is covered by the output schema, so this is a solid addition.

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, with the retrieval purpose front-loaded before the alternative-tool pointer. 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?

With one documented parameter, an output schema, and safety annotations already in place, the description covers what an agent needs: what is fetched, how to find URLs, and the paywall caveat. Minor gap is that it does not hint at content limits or article fragmentation, but nothing essential 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?

Schema coverage is 100% and the single url parameter is fully described there. The description's mention of 'canonical URL' reinforces the schema but adds no new syntax or format detail, so the baseline 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?

States a specific verb (Fetch), resource (FT article), and scope (public metadata and body paragraphs) keyed on the canonical URL. It clearly differs from discovery siblings like ft_search and ft_headlines, which it names.

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 ft_headlines, ft_search, or ft_news to find stories, implying this tool is for retrieving a known article. It does not state hard exclusions, but the workflow context is unambiguous.

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