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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false. The description reinforces this with 'Reads only; nothing is created or modified' and adds additional context: API key requirement for unpublished articles, error behavior for non-existent/inaccessible slugs, and that it returns an article object with content_markdown populated. This exceeds what annotations provide.

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 three sentences, front-loaded with the main purpose, then usage context, then additional behavioral details. Each sentence contributes value without redundancy, achieving maximum conciseness.

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 tool with one parameter and comprehensive annotations, the description covers all necessary context: what it returns, when to use it, auth requirements, and error conditions. The presence of an output schema is not marked, but the description explicitly mentions the returned object and its field, making it complete.

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?

The sole parameter 'slug' is fully documented in the JSON schema (100% coverage) with a clear description, example, and exclusions. The description adds no extra parameter-specific information, but the schema is sufficient, so the baseline score 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 clearly states the tool fetches a single article by slug, including its full Markdown body. It distinguishes from sibling tools like list_my_articles and search_articles, which omit bodies, so the purpose is unambiguous and specific.

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?

Explicit guidance is provided: 'Use this after list_my_articles or search_articles has given you a slug and you need the actual content' and explains why fetching one at a time is deliberate. This clearly indicates when to use and differentiates from alternatives.

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