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

Beyond the annotations, it discloses the required auth header, the multi-step flow (approve + createEscrowWithProof + attach), the testnet-only restriction, and the absence of a REST analogue. None of this contradicts the readOnly/destructive/idempotent 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 front-loaded with the core action and each subsequent sentence adds distinct value: free alternative, auth, execution flow, wallet-type routing, and caller restrictions. It is dense but not bloated.

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 prerequisites, flow, constraints, and sibling routing are all covered, so an agent can invoke the tool correctly. The only minor gap is that, with no output schema, it does not hint at what the response indicates after funding succeeds.

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 explains that session_id is the UUID of a session opened via data_session_open. The prose description adds no parameter-specific detail, so the high-coverage baseline of 3 is appropriate.

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 verb and resource, 'Buy per-query access to live data listings,' and distinguishes itself from data_preview and data_session_funding_package by wallet type and preview availability. This makes the tool's purpose unambiguous relative to its siblings.

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 explicitly routes free first uses to data_preview and user-supplied-wallet cases to data_session_funding_package, and states the prerequisites (agent API key, testnet/sandbox wallet, not guest-callable). This gives an agent clear conditions for when to select this tool versus alternatives.

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