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

The annotations already declare the tool as read-only, idempotent, and non-destructive. The description adds valuable behavioral context beyond those hints: it guarantees a mandatory source_url and explicitly states that the full third-party article text is never returned, which is important for agents to understand output limitations.

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 two sentences, both dense with useful information: the first defines the return contract, the second explains the use case. No wasted words, and the key behavioral constraint (never full third-party text) is front-loaded.

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 presence of a full output schema, rich annotations (read-only, idempotent, non-destructive), and complete parameter documentation, the description covers all needed context for an agent to invoke the tool correctly. It also explains the output's nature and the intended grounding use case, making it sufficiently complete.

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?

The input schema has 100% coverage with all three parameters described, so the baseline is 3. The description adds minimal parameter-level detail beyond the schema; it mentions 'recent' news and 'ticker' implicitly, but does not enrich the meanings of limit or days_back beyond what is already in the schema.

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 clearly states the tool returns the latest news for a ticker, listing the specific content (headline, short summary, mandatory source_url), which precisely defines its function. It distinguishes itself from sibling tools by focusing on per-ticker news rather than broader search or market context.

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 explicitly recommends using it 'to ground a market read in recent, attributable news,' providing a clear use case. It does not explicitly mention when to prefer alternatives like public_search_news, but the ticker-specific scope makes the intended context clear.

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