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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe read operation. The description adds some extra context: no API key needed, price 0.01 USDC/query, max 20 queries/session, and that it's free. These are useful but don't describe the return format or what happens with the 'question' parameter. The description does not contradict the annotations, so a 3 is appropriate.

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 verbose and marketing-heavy, filled with emojis and repeated phrases ('FREE preview', 'no key, no payment'). It front-loads promotional language rather than essential functional info. It is not concise or well-structured for an agent; it reads like an ad for a human. The core function is buried under sales copy.

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 tool with only two optional parameters and no output schema, the description should explain what the tool returns and when to use it. It does not mention that it returns public metadata, does not clarify the default behavior of 'slug' when routed via /mcp/data/{slug}/http, and does not explain the purpose of the 'question' parameter beyond what the schema says. The tool is simple but the description leaves essential context missing.

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%: both 'slug' and 'question' are documented in the schema, including defaults and behavior (e.g., question is echoed back). The tool description adds no parameter-specific detail beyond mentioning sample questions, which are not parameter semantics. With high schema coverage, the description carries no extra burden, so 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 is promotional rather than functional. It says 'FREE preview' and mentions 'Listing: nasaiotd', but does not explicitly state that this tool returns public metadata for a given listing slug. The schema's own description ('Free, guest-callable taste of a listing') is clearer than the tool description. The purpose is implied but not clearly articulated.

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?

No guidance on when to use this tool versus any alternative. It instructs 'call this now' but provides no context about when a preview is appropriate, when not to use it, or how it differs from sibling tools like data_session_query or data_session_open. The sample questions are aimed at end-users, not at helping an agent decide when to invoke this tool.

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