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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and external-access profile is covered. The description adds useful context beyond this by identifying the source as a public feed and the stream as the general top-story stream, though it does not discuss rate limits, freshness, or pagination. Given the annotation coverage, a 4 is appropriate.

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?

Four tight sentences, each earning its place: the first defines the tool, and the remaining three route the agent to the correct sibling tool for adjacent needs. The routing guidance is front-loaded after the core definition, making the description easy to scan.

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 parameterless top-stories endpoint with annotations covering safety and an output schema present, the description is complete. It states what is returned (headline items from the general stream) and provides clear routing to rte_headlines, rte_sections, and rte_article, so no critical invocation context is missing.

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?

This tool takes no parameters, so the baseline is 4. The description adds no parameter semantics because there are none, and it correctly avoids inventing inputs for an endpoint that accepts none.

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 verb and resource: fetch RTÉ News top stories from the public feed and return headline items from the general top-story stream. It explicitly distinguishes this tool from rte_headlines (section-specific) and rte_article (single story body), so an agent can route correctly without opening sibling schemas.

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 explicit when-to-use guidance: use rte_headlines for section-specific lists, rte_sections to discover section slugs, and rte_article when a single story body is needed. The alternatives and the conditions that select them are named directly, leaving nothing to inference.

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