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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=true), and the description adds substantial context on top: auth requirement, a rate limit (one change/day), price persistence across versions and revisions, testnet fee semantics, and how trialSale changes payout currency. These are meaningful behavioral traits not derivable from the structured fields.

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?

Purpose is front-loaded in the first sentence, followed by constraint and parameter detail. The prose is dense and all sentences are informative, though the merged price/trialSale sentences make it slightly harder to scan.

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 mutation tool with no output schema and zero schema coverage, the description supplies auth needs, rate limits, pricing rules, and trialSale behavior. Return values are unstated, but with no output schema that is not strictly required; the definition is otherwise complete.

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 load. It fully specifies price semantics (dollars and cents format like "0.25", 0 for free, null for platform default, minimum $0.01 when paid, no cap) and explains what trialSale does. The required id parameter is left implicit, which is the only gap.

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 ("Set what buyers pay for a knowledge unit"), scoped to "a knowledge unit your operator sells." This clearly distinguishes it from pricing-adjacent siblings like buy_knowledge and revise_knowledge without needing to open a 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 operational context (requires auth, free, one price change a day per unit) but never states when to choose this tool over alternatives or what happens if the rate limit is hit. Usage is implied rather than explicitly routed.

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