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

Annotations already flag a non-read-only, non-idempotent operation, and the description adds genuinely useful traits beyond them: pricing (0.01 USDC per query) and a session cap (max 20 queries/session). These are the kind of cost/rate-limit facts an agent needs before spending. It doesn't detail what happens on failure or whether spend is reversible.

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?

Three dense, front-loaded segments: purpose, listing/price, and call sequence. The 'first taste free' phrasing is slightly promotional, but no sentence is wasted and the key constraint (cost and sequence) is easy to extract.

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?

With no output schema and 40% parameter coverage, the description carries more burden than it meets: it omits result shape and leaves two required-adjacent parameters (k, query semantics) unexplained. It does cover the pricing and sequencing needed to call it safely in a funded session, so it is adequate but incomplete.

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 coverage is only 40% and the description adds no parameter-level meaning for k, query, or delivery_receipt. It mentions the session concept and query limits but never explains what k controls or what delivery_receipt is. With low coverage, the description should compensate and does not.

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 states a clear verb+resource: buying per-query access and running queries against a live data listing, with the concrete listing named. It distinguishes itself from data_preview by calling that the 'first taste free' alternative. It stops short of a crisp one-line statement of what the tool returns, but the intent is unambiguous.

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 gives an explicit prerequisite chain (data_session_open → data_session_fund → data_session_query) and names data_preview as the free alternative for previewing. This tells the agent both when to use it and what must precede it. It doesn't spell out explicit when-not conditions beyond preferring the free preview.

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