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

Annotations only indicate non-read-only, non-idempotent behavior; the description adds meaningful context by disclosing the 0.01 USDC per-query cost, the 20-query per-session cap, and the required session lifecycle. This goes beyond the structured annotations and helps an agent understand the paid and stateful nature 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 compact and front-loaded, with the core paid-query purpose in the first sentence followed by pricing and sequence details. Every sentence adds useful information, and there is no wasted verbiage.

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 description covers the commercial and sequential context well, but with no output schema and low parameter coverage, an agent still lacks information about what the query returns and how optional receipt parameters behave. It is adequate for high-level invocation but incomplete for fully correct standalone use.

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 only 40%, and the tool description does not compensate by explaining key parameters like query, k, delivery_receipt, or sandbox_receipt. It only implies session_id through the sequence. This leaves an agent under-informed about required and optional parameter semantics.

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 names a concrete resource (live data listings, specifically usnwatch Ubuntu Security Notices) and frames the action as paid per-query access, which is distinct from the related data_session_open and data_session_fund steps. It is not a tautology and the sequence line helps position the tool as the query step. However, the verb 'buy' is slightly indirect compared to schema's clearer 'Run a prepaid query'.

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 explicitly points to data_preview for a free first taste and gives the required sequence data_session_open → data_session_fund → data_session_query, so an agent knows this tool is used after the session is funded. It does not spell out exclusions such as when to use other data-related siblings, but the preconditions and free-preview alternative are clear.

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