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

Annotations already declare readOnlyHint=true, so the agent knows this is a safe read. The description adds useful output details (title, body, author, reviewer, citations, metadata) but does not disclose error handling or rate limits. Given the read-only annotation, the additional context is moderate, not rich.

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?

The entire description is one efficient sentence: it front-loads the verb and resource, then lists expected return fields. Every clause adds value, and there is no repetition or extraneous detail.

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 simple single-parameter read operation with a read-only annotation, the description adequately covers the purpose and return content. It could mention how to find the slug (via list_articles or search_articles), but sibling tools imply that. Missing error semantics is acceptable given the tool's simplicity.

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% because the only parameter 'slug' has a description ('Article slug'). The description reinforces 'by slug' but adds no new meaning beyond the schema. With high schema coverage, baseline of 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?

The description uses a specific verb 'Fetch' and identifies a precise resource ('a single article from Psychiatry for Teens') with a clear lookup method ('by slug'). This clearly distinguishes it from siblings like list_articles and search_articles, which handle broader set operations.

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?

The phrase 'Fetch a single article... by slug' clearly implies use when a specific slug is known and full article content is needed. However, it does not explicitly mention when not to use it or name alternative tools, though sibling names provide implicit context.

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