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

Annotations already provide readOnly=true, idempotent=true, and destructive=false. The description adds useful non-obvious details: no auth needed, cost per query (0.01 USDC), and a rate limit (max 20 queries/session). It does not contradict the annotations, and 'public metadata only' in the schema description adds further behavioral clarity.

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 front-loaded with the most important signal ('No API key needed — call this now') and includes useful sample content. However, it has marketing repetition: 'No API key needed', 'FREE preview — no key, no payment', and 'Try one of the sample questions now' say similar things multiple times.

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 simple tool with two optional parameters, the description plus schema covers the listing, cost, rate limit, free access, and example questions. Return format is not described, but the schema description's 'public metadata only' partially mitigates that gap.

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 coverage is 100%, so the baseline is 3. The description adds concrete parameter usage by naming the specific slug ('hnfrontpage') and providing two realistic sample questions, which helps an agent know exactly what to pass for 'question.'

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 identifies the exact resource ('Listing: hnfrontpage: Hacker News Front Page (Live)') and frames the tool as a free preview with sample questions. It clearly separates this from paid session tools by emphasizing 'FREE preview — no key, no payment.'

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 a strong 'when to use' signal: call now, no API key, no payment, with sample questions. However, it never names sibling tools like data_session_query or states when NOT to use this preview, so routing vs alternatives is left implied rather than explicit.

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