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

The description adds behavioral context beyond the annotations by disclosing the cost model (0.01 USDC/query, max 20 queries/session) and the prepaid, session-based workflow. It does not contradict the annotations, but it omits important side effects such as what session resource gets created, whether any upfront payment occurs, or what authentication/escrow prerequisites exist.

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 concise and front-loaded with the core purpose, then gives workflow guidance. The specific 'Listing: certfrwatch...' detail may be more than necessary and could be mistaken as a restriction rather than an example, but overall it is efficient and readable.

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 6 parameters, no output schema, and minimal annotations, the description is not complete enough to invoke reliably. It does not explain what the open session returns, how to supply proof_escrow_id or open_tx_hash, or what happens after opening regarding funding and querying beyond a vague sequence.

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 documents listing_id, listing_slug, and buyer_address, and the root schema description explains slug-or-UUID selection and the default wallet behavior. The tool description adds useful hints about max queries per session and gives a concrete listing example. However, open_tx_hash and proof_escrow_id remain semantically unexplained, and with 50% schema coverage the description only partially compensates.

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 action: 'Buy per-query access' and 'Open a prepaid session', naming the resource as live data listings and a specific listing (certfrwatch). It distinguishes itself from the free preview (data_preview) and implies the follow-up steps of funding and querying, though it does not explicitly name sibling tools.

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 useful workflow context: users should first try data_preview for free, then open a prepaid session, then fund and query. However, it does not explicitly explain when to use this tool versus alternatives such as data_session_fund, data_session_query, or attach_escrow, nor does it state exclusions like 'if a session is already open'.

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