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

Annotations declare readOnlyHint=true and destructiveHint=false, and the description clarifies that the tool 'returns fund instructions' rather than executing a payment. This reduces the risk of the agent assuming a direct purchase. Still, the word 'Buy' is slightly misleading given the read-only annotation, and the description does not explain whether any state changes occur or what the returned instructions are meant for.

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?

Two compact sentences deliver the purpose, target listing, pricing, prerequisite, and relationship to data_preview. No filler or redundant repetition of the schema.

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 tells the user the prerequisite (data_session_open) and the output type ('fund instructions'), but it does not explain what to do with those instructions or mention the related data_session_fund / data_session_attach_escrow tools. Without an output schema or further guidance, an agent may not know the next step.

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 already documents session_id as a UUID from data_session_open, and the description reinforces the 'after data_session_open' context. There is no additional parameter-level detail, but the schema covers the necessary meaning, so the baseline score of 3 is appropriate.

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 clear action ('Buy per-query access'), names the exact listing (cratewatch), and notes the pricing. It also implicitly differentiates from data_preview (free taste). However, it does not distinguish itself from the similarly named sibling data_session_fund, leaving some ambiguity about which tool actually performs the funding step.

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?

Provides explicit workflow guidance: try data_preview first for free access, and this tool returns fund instructions after data_session_open. This gives an agent a clear sense of sequencing. It stops short of saying when not to use it or how it relates to data_session_fund/data_session_attach_escrow, but the core usage context is present.

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