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

Annotations only carry the generic safety profile (readOnly=false, idempotent=true, destructive=false), while the description adds rich behavior: exact pricing and tax treatment, no-credits/subscription model, the required payments:schema-repair key, billing-identity and B2B-terms requirements, and the critical warning that payment credentials must never appear in arguments. This is well beyond what annotations provide.

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-loaded with the core action and pricing, and every sentence carries substantive constraints (auth, alternative path, credential warning). It is dense and runs long as a single block, but there is little wasted text.

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 10-required-parameter mutation tool with no output schema, the description covers pricing, gating prerequisite, auth requirements, and the alternative card flow. It stops short of describing idempotency semantics or what a successful/failed order returns, which are the main remaining gaps.

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 11 parameters, so the description carries the burden and it partially compensates: it anchors locale/currency to the FR/EUR vs US/USD pricing, implies max_amount_minor=200, and explains the terms/business/professional/authority confirmations. However, inspection_id, idempotency_key, source_html_sha256 and url semantics are never clarified, leaving several parameters undocumented in both schema and prose.

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 ('Buy one eligible WebPage JSON-LD correction with evidence, validation and one live check') and clearly differentiates from siblings like kanonyr_buy_technical_audit and kanonyr_verify_schema_repair. An agent immediately knows this is the paid schema-repair purchase path.

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 prerequisite and names the sibling that gates it: 'Only buy after inspect_page reports eligible.' It also documents an alternative path ('owner may instead open card_payment_url') and a stop condition ('stop on conflicts').

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