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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and network-exposure behavior is covered. The description adds only the freshness qualifier ('Current') and the section provenance constraint; it says nothing about result count, ordering, or pagination. Adequate but thin beyond what annotations supply.

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 front-loaded sentence with no filler; the scope, resource, and constraint all appear before any trailing detail.

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?

With an output schema present, the description need not explain return values, and it covers the one input and its dependency. For a simple list tool this is essentially sufficient; only the section-value format is unresolvable from the definition alone.

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 0% for the single parameter, so the description must carry the semantic load. It does so by constraining `section` values to those returned by metro_sections, which is meaningful domain information; only the expected format/casing of a valid section string is left unstated.

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 ('Current Metro headlines') scoped to 'one public section', which cleanly separates it from metro_sections (section list) and metro_article (full article). It does not explicitly contrast with metro_news, so sibling differentiation is only partial.

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 the key precondition that the `section` value must come from metro_sections, which is actionable routing guidance. It stops short of stating when to prefer this over metro_news or metro_article, but the required-parameter dependency is clearly conveyed.

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