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

Annotations already declare readOnly=false, idempotent=true, and destructive=false. The description adds meaningful behavior context: the auth requirement, the guest-call restriction, and the POST endpoint. It does not mention what happens after attachment or any settlement details, but there is no contradiction with the supplied annotations.

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 five short sentences, each adding distinct value: purpose, free alternative, auth, attach semantics, guest restriction, and endpoint. There is no redundant restatement of the title or schema, and the most important purpose is front-loaded.

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?

The description covers purpose, auth, alternative, endpoint, and the choice between open_tx_hash and proof_escrow_id. It does not explicitly state the prerequisite that the session must have been opened via data_session_open, though the schema's session_id description does mention that. Since there is no output schema, a note on expected return values or next steps would improve completeness, but the description is largely adequate.

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 only documents session_id; open_tx_hash and proof_escrow_id have no property-level descriptions. The description compensates by stating that open_tx_hash is preferred over proof_escrow_id, clarifies they refer to a buyer-funded proof escrow, and ties them to the attachment action. This gives the agent the decision guidance the schema lacks.

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: attach a buyer-funded proof escrow (identfied by open_tx_hash or proof_escrow_id) to an opened data session, framing it as buying per-query access. This is distinct from siblings like data_session_open, data_session_und, and data_session_query because it focuses on the escrow-attachment step. The verb 'attach' is specific and the resource 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 names data_preview as the free-taste alternative, specifies authentication requirements (agent API key with Bearer or X-API-Key), states that the tool is not guest-callable, and gives the exact REST endpoint. It does not explicitly sequence this tool relative to data_session_und or data_session_funding_package, so the agent must infer some workflow ordering.

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