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

Annotations already declare openWorld=true, idempotent=true, destructive=false, readOnly=false, so the safety profile is covered. The description adds meaningful behavior beyond that: the exact payment prerequisites and the retry rule 'Same idempotency key and input for every retry', plus what the purchase does not include. It doesn't describe delivery mechanics or when a result becomes available.

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?

Four compact sentences, front-loaded with price and product so the agent reads the essential facts first. The middle clauses are terse to the point of being jargon-heavy ('Explicit payments:technical-audit key', 'Stripe MPP payment'), which costs a bit of readability.

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 paid, mutating, open-world tool with 9 constrained parameters and no output schema, the description covers payment prerequisites, idempotent retry behavior, deliverable scope, and exclusions. An agent can call it correctly; only the meanings of the individual confirmation flags remain unstated.

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% across 9 parameters, so the description carries the full explanatory burden. It partially compensates – locale/currency via the FR/EUR and US/USD pricing, idempotency_key via the retry rule, the billing-identity confirmations via 'validated ... business billing identity', and urls implicitly via '2–5 page' – but terms_accepted and authority_confirmed are never explained and the const max_amount_minor is only inferable from the stated price.

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 concrete verb and resource with scope and price: 'Buy the existing 2–5 page technical audit for EUR 5 (FR) or USD 5 (US)'. The resource ('technical audit') is clearly distinct from the sibling kanonyr_buy_schema_repair, though the description never names that sibling to make the routing explicit.

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 preconditions for use (payments:technical-audit key, authorized Stripe MPP payment, validated FR/EUR or US/USD business billing identity) and states a scope boundary ('no remote publication or AI citation measurement') that implicitly separates it from the publication-check siblings. It stops short of explicitly naming the alternative tool to pick instead.

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