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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely non-obvious behavior: the front-matter fields included, the French fallback when no English edition exists, and that the fallback is signaled in the output. It doesn't cover failure modes for an invalid id.

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, each carrying distinct information, with the primary payload (full text plus front matter) front-loaded and mode differences second. No filler or restatement of the title.

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 annotations and an output schema present, the description covers the modes, locale fallback, and content shape well. The remaining gap is procedural: no hint that ids typically come from search results, nor what happens on an unknown or malformed id.

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 67%, and the description compensates for the undocumented gap: the 'format' enum has no schema description, yet the description explains what summary and outline yield versus full. It also reinforces the French fallback tied to 'locale'. It adds no detail on accepted id forms beyond what the schema already states.

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 and resource ('The full text of one article or news brief') plus the exact rendering (Markdown with front matter and references). It clearly reads one piece rather than listing or searching, though it never names a sibling such as search or related to route the agent explicitly.

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?

Gives usable selection guidance among the tool's own modes — 'format summary gives the front matter and summary only; outline gives the section headings' — so an agent knows when to pick a lighter format. It stops short of saying when to use this tool instead of siblings like search, related, or series.

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