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

The description discloses that it's a paid operation ('Buy per-query access') and that opening a session may default the buyer to the caller's own wallet. It does not explicitly mention non-idempotency, but annotations already flag that; the description adds useful context about cost and session setup.

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 overly long and includes implementation details like 'type: ignore[assignment]' and pydantic override mechanics that are irrelevant to an agent. The core purpose is front-loaded, but the extraneous technical discussion harms conciseness.

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?

There is no output schema, and the description does not state what the tool returns (e.g., session ID, status). It also omits potential errors or failure modes. An agent would not know what to expect after calling this tool.

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 descriptions cover only 3 of 6 parameters, and the tool description explains the slug/UUID choice and buyer_address default. However, open_tx_hash, proof_escrow_id, and max_queries are not semantically explained in either the schema or the description, leaving gaps for the agent.

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: 'Buy per-query access to live data listings' and 'Open a prepaid session'. It differentiates from the free preview tool ('first taste free via data_preview') and from later steps (fund, query), making its role distinct among siblings.

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 provides a clear workflow: use preview first for free access, then open a session, then fund and query. It also explains when to use slug vs. UUID and the buyer_address default, giving practical guidance on when this tool is appropriate.

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