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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds value by clarifying the error behavior (returns error object, never raises protocol errors), the 20-headline limit, and the scoring dimensions. However, it doesn't mention whether the order of ties is deterministic or any rate limits. Still, with strong annotations, the bar is low, and the added context is helpful.

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 reasonably concise at ~6 sentences, with critical info front-loaded (purpose, free, example). The second paragraph adds usage guidelines and error behavior efficiently. Minor structural improvement: the error handling sentence could be a separate paragraph, but overall it's well-organized and every sentence earns its place.

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?

The description covers purpose, usage boundaries, input/output example, error handling, idempotency/read-only safety, and points to relevant siblings. Given the tool's simplicity (1 param, clear schema, rich annotations, output schema present), this is a complete and self-sufficient description that leaves little ambiguity for an AI agent.

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 documents the single parameter ('headlines') well, including that only the first 20 are scored. The description reinforces this with an example but adds little new about parameter syntax or constraints beyond what the schema provides. Baseline 3 is correct.

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 starts with a specific verb ('Score and rank'), names the resource ('headlines'), and clarifies the scope ('up to 20 headlines, best first'). The example input/output reinforces the purpose, and it clearly distinguishes from siblings like analyze_writing which handles body prose.

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 states when to use ('several title options need ranking') and provides clear exclusion criteria: 'Not for email subject lines' (pointing to subject_line_scorer) and 'not for body prose' (pointing to analyze_writing). It also discusses error handling and retry safety, giving the agent full context.

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