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

Annotations declare a destructive, idempotent write, and the description adds rich context beyond them: auth requirement, no wallet, testnet USDC credit mechanics, idempotency semantics ('Buying a version you already hold charges nothing'), failure behavior ('the answer carries the top-up URL'), and downstream effects on read_dataset/query_dataset/dataset_manifest/dataset_diff.

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 critical 'Spends money' warning is front-loaded and every sentence carries operational content (auth, defaults, downstream tools, edge cases). It is dense with URLs and parentheticals that make it longer than necessary, but little is truly wasted.

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 purchase tool with no output schema, the description covers what an agent needs: cost/auth prerequisites, when to call, version default, idempotency, downstream read coverage, and the failure/top-up path with my_quota for balance. Nothing material is missing.

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 0%, so the description carries the burden. It usefully documents the version default ('The latest version unless one is given') but says nothing about the required slug format or constraints, leaving half the parameters to the schema's bare type/pattern definition.

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 verb and resource ('buys a version of a paid dataset') with the payment mechanism front-loaded ('Spends money... prepaid credits'). An agent can distinguish this paid-dataset purchase from buy_knowledge and buy_knowledge_with_credits without opening the schema.

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 a clear gating condition ('Call it only when the user asked for this dataset or approved the purchase') and a default-versus-explicit rule ('The latest version unless one is given'). It stops short of naming which sibling purchase tool to use instead for non-dataset resources, so it's clear context without full alternative routing.

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