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

The description adds substantial behavioral detail beyond the annotations: it is keyless, queries two engines in parallel, fuses results by reciprocal rank, deduplicates by normalized URL, groups variants under also_on, and reports which engines carried each item with 'via: both' as the strongest signal. This fully explains the operation's mechanics and output semantics.

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 three dense sentences with no filler. It front-loads the core behavior first, then gives the usage guideline and sibling distinction. Every clause earns its place by adding either behavioral precision or routing guidance.

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 read-only search tool with rich annotations and no output schema, the description covers sources, fusion/deduplication logic, output item fields, publisher attribution, engine provenance, and the sibling boundary. An agent has what it needs to decide when to call the tool and what to expect back.

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 high at 83%, so the schema already documents most parameters individually. The description adds little parameter-level meaning; its main parameter-related hint is the general usage framing, but it does not elaborate on query, lang, region, when, limit, or task_context beyond what the schema provides. 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 names a specific verb and resource ('news search'), identifies the concrete data sources (Google News RSS and Bing News RSS), and explicitly contrasts itself with feed_items ('use feed_items for one site's own posts'). An agent can distinguish this tool from its siblings without opening the schema.

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 states a clear use case ('Use for "what is the news about X"') and explicitly routes the agent away from this tool when the goal is a single site's posts ('use feed_items for one site's own posts'). This is direct, actionable guidance rather than implied context.

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