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

Annotations only signal readOnly=false, so the description adds crucial behavioral context: this is a paid/prepaid operation, requires authentication, is not guest-callable, and can trigger sandbox receipt signing via sandbox_receipt. It does not detail fund consumption or failure effects, but the added context goes well beyond 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?

Four dense sentences with no filler. The main action and alternative are front-loaded, and the auth requirement, endpoint, and sandbox behavior are each given in one compact clause. Every sentence earns its place.

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?

Covers purpose, prerequisites, auth, endpoint, and the sandbox receipt option, but with no output schema it only vaguely describes the return as 'attested hits plus a purchase receipt.' The semantics of k and delivery_receipt are still missing, so an agent is not fully equipped to call 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 coverage is low (40%), and the description only meaningfully explains sandbox_receipt. Parameters k, query, and delivery_receipt remain semantically unclear; delivery_receipt in particular appears only as a schema title with no guidance. The description does not compensate enough for the schema's gaps.

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?

States a specific action: 'Run a prepaid query against a funded data session' and the resource: 'data-sessions/{session_id}/query'. It also names the outcome ('attested hits plus a purchase receipt') and differentiates itself from data_preview via 'first taste free via data_preview'.

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?

Gives explicit prerequisites: a funded data session and an agent API key, and says 'Not guest-callable.' It also points to data_preview as the free alternative, making the when-to-use/when-not-to-use decision clear.

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