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

The annotation readOnlyHint=true already signals a safe read operation. The description adds value by disclosing the exact return fields (title, body, author, clinical reviewer, citations, metadata), which goes beyond the annotation and gives the agent a concrete expectation of the response.

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 description is two sentences, front-loaded with the action and resource, and lists return contents without any filler. Every sentence contributes meaningful information, making it highly efficient.

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 one-parameter, read-only tool with no output schema, the description fully covers the purpose, the parameter, and the return contents. It gives the agent everything needed to call and interpret the tool correctly, without unnecessary details.

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%, with the 'slug' parameter already described as 'Article slug.' The description only reinforces 'by slug' without adding deeper semantic detail, such as format or uniqueness constraints. The baseline of 3 is appropriate since the schema does the heavy lifting.

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 the specific verb 'Fetch' and identifies the resource as 'a single article from Psychiatry for Children by slug.' This clearly differentiates it from siblings like list_articles and search_articles, which handle multiple or filtered articles.

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 description makes the context clear: use when you need a specific article by slug. While it doesn't explicitly mention alternatives or exclusions, the 'by slug' phrasing implies the usage scenario. It lacks an explicit 'use list_articles for multiple' note but is otherwise clear.

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