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

Annotations already declare non-read-only, non-idempotent, and non-destructive behavior. The description adds meaningful behavioral context: paid access at 0.01 USDC per query, a maximum of 20 queries per session, and the required prerequisite workflow. It does not discuss failure modes or insufficient-funds behavior, but the pricing and limit details are valuable.

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?

Three sentences with no filler: purpose, pricing, listing, and workflow sequence are all packed efficiently. The most important usage constraint (free preview alternative) is front-loaded.

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?

With 5 parameters, no output schema, and minimal annotation detail, the description should carry more weight. It covers the workflow prerequisites and pricing but omits parameter semantics, expected return data, and error/edge-case behavior. An agent would still need to inspect the schema closely to call this 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 description coverage is only 40%, so the description needed to compensate for undocumented parameters like k and delivery_receipt. It does not explain any parameter meaning, valid query formats, or the role of sandbox_receipt. This is a significant gap for an agent trying to invoke the tool correctly.

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 the tool buys per-query access to live data listings and identifies the specific rustsecwatch listing and pricing. The workflow sequence makes it clear this is the query step after data_session_open and data_session_fund. The first verb 'buy' is slightly imprecise for what is ultimately a query operation, but the context disambiguates it.

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 lays out the exact sequence data_session_open → data_session_fund → data_session_query. This gives strong routing guidance, though it does not explicitly state 'when not to use' beyond the free-preview alternative.

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