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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral context: no API key required, no payment required, a 20-queries-per-session limit, and the fact that it is a free preview. The 'Price 0.01 USDC/query' line is somewhat ambiguous against 'FREE preview,' but it does not contradict the annotations.

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 padded with marketing language, emojis, repeated 'no key/no payment' statements, and a direct call-to-action ('Try one of the sample questions now'). It front-loads the key message but is not tight or information-dense. Several sentences could be removed without losing functional 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 simple, read-only preview tool with no output schema, the description covers access, cost, and usage examples. However, it does not clearly state what the tool returns, and the combined 'Price 0.01 USDC/query' with 'FREE preview' creates ambiguity. The schema's mention of 'public metadata only' helps, but the main description leaves the response semantics under-specified.

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 already fully describes both parameters, so baseline is 3. The description contributes sample questions that illustrate the 'question' parameter's intent, but it does not add meaningful guidance about the 'slug' parameter or how to choose a different listing. It adds some value but does not go beyond the schema meaningfully.

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 identifies the tool as a free preview of a data listing and even gives sample questions to ask. It implies a read-only preview action, though it never explicitly states 'returns public metadata' in the main description. The 'FREE preview' phrasing helps distinguish it from paid data-session tools, but the distinction is implicit rather than named.

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 gives direct usage context: no API key is needed, it is free, and the user should try sample questions now. This strongly signals when to call the tool. However, it does not explicitly mention alternatives like data_session_query or state when NOT to use this tool, so it stops short of full routing guidance.

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