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

The description implies financial commitment ('Buy per-query access') and a session lifecycle, which adds behavioral context beyond the annotations. It does not explicitly mention side effects like charging or failure, but the key actions are evident.

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 main description is short, direct, and packed with relevant information. It front-loads the core action and pricing, making it easy for an agent to grasp quickly.

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 explains the workflow but omits what the tool returns (e.g., a session ID needed for subsequent funding/querying calls). Given the complexity of a multi-step session, this missing output context is a noticeable 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?

Only 3 of 6 parameters have descriptive text (listing_id, listing_slug, buyer_address). The schema description provides context for the listing identifier choice and buyer_address default, but max_queries, open_tx_hash, and proof_escrow_id remain semantically unclear beyond their constraints.

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's purpose: buying per-query access to a data listing and opening a prepaid session. It specifically names the listing and pricing, and distinguishes it from the free preview alternative.

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 mentions when to use the tool (after preview, before funding/querying) and references the free preview as an alternative. It also explains the workflow of opening a prepaid session, but does not exhaustively compare with all sibling tools.

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