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 meaningful context ('Current' freshness, section must be sourced from sun_sections), but discloses nothing about scope limits, result counts, or ordering beyond that.

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?

One front-loaded sentence with zero padding; the resource and its scoping constraint are the only two things stated, and both earn their 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 the single required parameter plus its source are documented. Only minor gaps remain (no result-count or ordering expectations), which is small for a one-parameter read tool.

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% and the single parameter's documented slug values are already listed in the schema. The description's only addition is pointing to sun_sections as the authoritative source, which is marginal but useful. Baseline 3 is correct when 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?

States a specific verb+resource+scope: current The Sun headlines from a single public section. An agent can distinguish it from sun_article (full articles) and sun_sections (the section catalog) without opening the schema. It stops short of explicitly contrasting with sun_news, so it is not a full 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?

Gives a real prerequisite ('section must come from sun_sections'), which routes the agent correctly for valid inputs. However it never states when to prefer this over siblings like sun_news or sun_article, so usage is only implied.

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