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

Annotations already convey idempotency and non-destructiveness. The description adds meaningful behavioral context: it is a paid operation, requires a specific auth method, is not guest-callable, and binds an escrow to enable per-query access. This goes beyond the annotations without 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 purposeful sentences deliver purpose, prerequisites, and endpoint without redundancy. Every clause adds value: the free-taste pointer, auth requirement, escrow parameter guidance, guest restriction, and REST method.

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?

Given the tool has no output schema and only three parameters, the description covers what the tool does, how to authenticate, the endpoint, and how to choose between the two escrow identifiers. It could additionally mention what happens after attachment or error cases, but for this scope it is fairly complete.

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 description coverage is only 33%, so the description carries the burden for open_tx_hash and proof_escrow_id. It clarifies that open_tx_hash is preferred and proof_escrow_id is an alternative, providing meaning the schema lacks. However, it does not explicitly state that at least one of the two must be provided, leaving a small ambiguity.

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 opens with a specific purpose ('Buy per-query access to live data listings') and states the exact action ('Attach a buyer-funded proof escrow ... to an opened data session'). It names the REST endpoint and distinguishes itself from the sibling data_preview by positioning that as the free first taste.

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?

Clear context is provided: it requires an agent API key, is not guest-callable, and applies to an 'opened data session'. It suggests using data_preview for a free taste, implying this tool is for paid access, but it does not explicitly contrast itself with the related sibling data_session_fund.

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