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

Annotations already provide idempotentHint, readOnlyHint, and destructiveHint. The description adds meaningful financial context: the cost is 0.01 USDC/query, there is a free preview path, and funding is platform-executed. It does not contradict the annotations and enriches the agent's understanding of the side effects of the call.

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 brief and front-loaded with the core purpose. The specific listing and price add useful context without excessive verbosity. Minor noise: the concrete 'quakewatch' listing could be mistaken for the only supported listing rather than an example, but it does not seriously harm readability.

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?

This is a low-complexity tool with a single required parameter, a fully described schema, and useful annotations. The description covers the essential flow (preview → fund → query) and the pricing model. It does not describe the response shape, but the absence of an output schema and the simple nature of the operation make this a minor gap.

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 input schema covers 100% of the parameter semantics: session_id is described as the UUID of a data session from data_session_open. The description adds no additional parameter detail, so it offers no value beyond the schema, which is acceptable per baseline.

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: buying per-query access to live data listings, with the outcome that the platform executes funding so the session can be queried. It names related tools (data_preview, data_session_query) as part of the workflow, though it does not explicitly distinguish itself from data_session_funding_package or data_session_attach_escrow.

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 implies a workflow: try free via data_preview, then fund, then use data_session_query. This gives useful sequencing context. However, it does not explicitly state when to choose this tool over its closest siblings like data_session_funding_package or data_session_attach_escrow, so the agent must infer the boundary from the name and schema.

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