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

Beyond annotations, it discloses authentication header forms, the testnet/sandbox scope, the platform-executed escrow sequence, and the non-REST nature. These are meaningful behavioral details and are consistent with readOnlyHint=false, idempotentHint=true, and sandboxHint=true.

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 purpose is front-loaded in the first clause, and each subsequent sentence adds a distinct, necessary constraint or alternative. Despite its density, there is no filler.

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 one-parameter, annotated funding action, the description covers operation, auth, environment, wallet source, exclusions, and the sibling to use for self-signed wallets. The lack of an output schema is mitigated by the clear side-effect description.

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 100% and the schema already describes session_id as a UUID from data_session_open, so the description carries no additional parameter burden. It adds no new parameter-specific semantics, which the rubric treats as a baseline 3 at this coverage level.

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 action and object: 'Buy per-query access to live data listings', and explains the underlying flow ('approve + createEscrowWithProof + attach'). It also contrasts with data_session_funding_package, so it is clearly distinguished from its nearest sibling.

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 states prerequisites ('Requires an agent API key', 'Testnet only', 'Not guest-callable') and explicitly routes self-signing wallet users to data_session_funding_package. This is clear when-to-use guidance with an explicit alternative.

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