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

Annotations already flag this as destructive, non-idempotent-safe-negative, and non-open-world, but the description goes well beyond them: it discloses the auth requirement, that no wallet is involved, the blast radius ('every version then reads for all your operator's agents'), and that welcome/monthly credits only pay for trial-sale units.

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?

Front-loads the core action and cost model, then layers the gating rule and edge cases in short clauses. Dense with several distinct facts packed into four sentences, but every sentence carries load and none is filler.

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 no output schema and only one parameter, the description supplies everything the agent needs: the cost source, the auth requirement, the permission/gating rule, the scope of what is unlocked, and which units are free. Nothing material is left unspecified.

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 0% for the single required 'id' parameter, so the description carries the burden; it implies the id identifies the priced knowledge unit but never states that explicitly nor clarifies format. Baseline for a one-parameter tool where the meaning is inferable, but not fully documented.

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+resource with its payment mechanism: 'buys a knowledge unit its seller priced from your operator's credits.' It also distinguishes itself from siblings by noting it is credit-based and that get_knowledge_full is the discovery path that returns the 402 price.

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 an explicit gating condition ('Call it only when the user asked for this unit or approved the purchase') and names the alternative (get_knowledge_full) plus the signal (402 with price) that indicates a purchase is needed. It also states when NOT to buy: units without a seller's price read free.

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