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

Annotations already declare readOnlyHint=true and openWorldHint=true, and an output schema exists, so the safety and return-shape burden is largely carried elsewhere. The description adds only the 'public' scope qualifier and the fact that body paragraphs are included; it says nothing about auth, rate limits, or failure modes. Minimal but non-contradictory addition earns a 3.

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?

A single compact sentence with the resource and payload front-loaded and no wasted words. It is efficient, though the noun-phrase framing is slightly less actionable than an explicit verb would be.

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 one-parameter fetch tool with an output schema and safety annotations, the description covers the essentials of what is returned. However, it omits any guidance on the URL parameter and on when to choose this over the sibling listing tools, leaving clear gaps.

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 single required 'url' parameter has 0% schema description coverage, so the description must explain the expected format (a Mirror article URL) and it does not. With coverage below 50%, the description fails to compensate for the gap.

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 identifies a specific resource (a Mirror article) and states the payload ('metadata and body paragraphs'), which lets an agent distinguish it from list-style siblings like mirror_headlines or mirror_news. The action verb is only implied ('One public Mirror article's...'), and no sibling is named, so it stops short of a 5.

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?

There is no when-to-use guidance and no mention of alternatives such as mirror_headlines, mirror_news, or mirror_sections. The agent must infer that this is the single-article fetch versus the listing tools purely from the name.

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