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

Beyond the annotations, it discloses authentication requirements, the guest restriction, the buyer-funded escrow prerequisite, and the preference for open_tx_hash over proof_escrow_id. It does not contradict the idempotentHint or destructiveHint annotations, though it does notfully describe side effects such as charges or session state changes.

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 composed of short, information-dense sentences with the core purpose front-loaded. It includes auth, prerequisites, parameter preference, and the REST endpoint without significant filler. There is slight overlap between 'Requires an agent API key' and 'Not guest-callable', but it remains efficient.

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 three-parameter action with no output schema, the description covers the endpoint, required auth, the need for an already opened session, and the key parameter choices. It does not mention response/error behavior or explicitly distinguish itself from data_session_fund, but an agent has enough information to invoke it correctly.

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 must compensate for the underdocumented open_tx_hash and proof_escrow_id parameters. It adds usable meaning by labeling open_tx_hash as preferred, proof_escrow_id as an alternative, and clarifying that these refer to a buyer-funded proof escrow. It does not explain proof_escrow_id semantics beyond that, but the preference guidance is genuinely useful.

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 verb+resource: attach a buyer-funded proof escrow to an opened data session, and adds the commercial purpose of buying per-query access. It references data_preview and data_session_open to show what the tool is not, but it does not explicitly contrast with data_session_fund or data_session_funding_package.

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 concrete usage context: requires an agent API key with Bearer or X-API-Key, is not guest-callable, and requires an already opened data session. It also suggests data_preview as the free first step. However, it does not explicitly say when to prefer data_session_fund or data_session_funding_package instead.

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