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

With no annotations provided, the description carries the full burden. It discloses 'No API key required', real-time retrieval, and the exact output fields. However, it does not explicitly mention rate limits, error behavior, or explicitly state that the operation is read-only, though this is strongly implied by 'Retrieves'.

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?

The description is well-structured and front-loaded with the core purpose, followed by return details, authentication note, usage scenarios, and exclusions. It is slightly longer than the minimal example, but each sentence contributes meaningful information with no filler.

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?

Given the lack of an output schema, the description compensates by listing the exact returned fields (headline, description, source name, URL, publication date) and the sort order. It also covers use cases, exclusions, and source limitations, making it complete for an agent to decide when and how to invoke the 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 description coverage is 100%, so the schema already fully documents all three parameters. The tool description adds minimal extra value beyond the schema, with the only additional insight being the tip about using a lower limit for a quick briefing. Baseline 3 is appropriate.

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 uses the specific verb 'Retrieves' and identifies exact sources (BBC News, The Guardian) and scope (nine topic categories). It also describes the return structure and sort order, and distinguishes itself from siblings by being the only news tool and explicitly contrasting with web_url_reader.

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?

The description provides explicit when-to-use guidance ('Use this tool when an agent needs current news...') and clear when-not-to-use guidance with an alternative ('Do not use this tool to read the full content... use web_url_reader instead', 'Do not use when news from sources outside BBC News and The Guardian is required'). This goes beyond implied usage.

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