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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that only public sections are served and that results are 'current', but says nothing about freshness windows, pagination, or result volume beyond that; modest added value over the annotations.

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 the input constraint front-loaded, no filler. Every clause earns its place.

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?

An output schema exists so return values need not be described, and annotations cover the read-only/open-world profile. The input contract is fully documented. Complete enough for an agent to call correctly, with only minor behavioral detail (freshness, result size) left implicit.

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 description coverage is 100% and the single 'section' parameter already enumerates 30+ documented values. The description adds the pointer that the value must be sourced from mirror_sections, which is marginally useful, but the schema does the heavy lifting, so baseline 3 applies.

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 states a specific resource and scope ('Current Mirror headlines for one public section'), making the operation clear. It references mirror_sections as the source of valid arguments but does not explicitly contrast itself with siblings like mirror_news or mirror_article, so differentiation is inferred rather than stated.

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?

It gives a clear prerequisite ('section must come from mirror_sections'), which tells the agent how to obtain valid input before calling. There is no explicit when-not or alternative-routing guidance, but the dependency guidance is genuinely useful.

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