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

Annotations already communicate mutability (readOnlyHint=false), idempotency, and non-destructiveness. The description adds some context—'platform-executes funding' and per-query pricing—but does not go deeper into side effects, such as what happens if the same session is funded twice. There is no contradiction with the 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 short, front-loaded with the action, and includes a useful pointer to the free preview alternative. The listing-specific detail about ghmcp and the 0.01 USDC/query pricing is concrete but somewhat narrow for a generic funding tool; still, the overall structure is tight and scannable.

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 simple one-parameter tool, the description plus annotations provide enough context to invoke it correctly: it explains what the tool does, how it relates to preview and query, and the session_id schema covers the only input. It does not describe the return value, but no output schema exists and the tool's success condition is fairly clear from the funding-to-query flow.

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 100%: session_id is fully documented as the UUID of a data session opened via data_session_open. The description adds functional context but does not need to repeat parameter details since the schema already covers them. This matches the baseline for high schema coverage.

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 states a specific action: 'Buy per-query access to live data listings' and 'Platform-executes funding so you can data_session_query.' It clearly identifies the resource as a data session and ties into the preview/query workflow. It does not, however, explicitly distinguish itself from data_session_funding_package or data_session_attach_escrow, which appear as 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?

The description provides clear sequence guidance: first taste free via data_preview, then fund the session, then use data_session_query. This is useful when-to-use context relative to two sibling tools. It does not explicitly say when not to use this tool or when to prefer data_session_funding_package or data_session_attach_escrow.

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