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

It explicitly says the tool 'Returns fund instructions after data_session_open,' which is a meaningful behavioral disclosure beyond the readOnly/idempotent annotations. The word 'Buy' is informal, but the returned-instructions framing aligns with the annotations rather than contradicting them.

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 compact sentences front-load the purpose and include the concrete listing and price. The phrase 'first taste free' is slightly informal but not wasteful.

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 single-parameter tool with no output schema, the description supplies the prerequisite, the alternative, the pricing, and the return behavior. It does not detail the exact content of the fund instructions, but that is a minor gap given the rich annotations.

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 schema already provides 100% coverage for session_id, and the description adds no new parameter-level detail beyond implying the session must already be open via data_session_open. This meets the baseline but does not exceed it.

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 identifies a specific action—buying per-query access to a named live data listing—and clarifies that the tool returns fund instructions rather than simply being a generic funding tool. It distinguishes itself from data_preview by framing the preview as free, though it does not explicitly contrast with data_session_fund.

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 context: use it after data_session_open and try data_preview first. It does not explicitly state when to use a sibling like data_session_fund or data_session_attach_escrow instead, leaving some routing ambiguity.

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