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

Beyond the readOnlyHint and destructiveHint annotations, the description details credit debits (1 credit on ok:true), response fields (credits_burned, credits_remaining), error structures (code/message/retryable/next), and specific error cases (401, 402). This is extensive behavioral disclosure beyond the annotations, with no contradiction.

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 description is a dense single paragraph that covers many edge cases, but it includes extraneous information like 'Install via GET https://shelf.kymac.co/llms.txt only' which is unrelated to the tool's operation. It lacks clear structure or sectioning, making it harder to scan, though every sentence carries some operational detail.

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 single-parameter tool with no output schema, the description thoroughly covers response fields, error handling, credit mechanics, and retry logic. It is sufficiently complete for an agent to invoke the tool correctly and interpret results without additional documentation.

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?

The schema already describes the url parameter with a clear definition and golden URL example (coverage 100%). The description reinforces the golden URL and adds the comparison concept, but does not introduce fundamentally new semantics beyond what the schema states.

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?

The description clearly states the tool runs a headless smoke test on a URL, referencing the POST /smoke endpoint and the golden URL comparison for ok true/false. It is distinct from sibling tools that manage credits or keys, and the verb-resource pairing is specific.

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?

It provides workflow guidance by advising to 'Quote first with quote_credits (no debit)' and explains credit debit conditions, which helps sequence usage. It does not explicitly name alternatives, but the context makes clear this is the tool for URL smoke testing, distinguishing it from credit/key operations.

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