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

Annotations already mark it read-only/non-destructive, and the description adds real behavioral context beyond them: nothing is charged, the quote expires in 10 minutes, a new edit on the short invalidates it, and the 402/payment escalation path. These are operational traits an agent cannot infer from readOnlyHint.

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?

Dense but front-loaded: purpose and the two kinds come first, then charging, returns, follow-up, and exclusions. The enumeration of return fields (quoteId, requiredCredits, availableCredits, affordable, expiresAt, facts) is partly redundant given an output schema exists, which costs a point.

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 quote tool feeding a paid mutation, the description covers the whole loop: input kinds, no-charge guarantee, quote lifetime and invalidation, how to spend the quote, and the insufficient-credits recovery path. Nothing an agent needs to call it correctly is missing.

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 100%, so the schema already documents all five parameters and the baseline is 3. The description adds genuine semantics on top: revoice needs beatIndex plus narration in the short's language and 'must fit that beat', while regenerate_shot takes beatIndex and shotIndex.

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 ('Quote one paid edit of a finished Topic Short before it runs') and immediately scopes it to the two paid edit kinds, which separates it from quote_topic_short (quoting the initial generation) and from the free-edit path. An agent can tell what this tool prices without opening the 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?

Explicitly says when to use it (before a paid edit runs), what to do with the result (pass quoteId with the same fields to edit_topic_short within 10 minutes), the failure branch (affordable false → edit_topic_short returns HTTP 402 → use create_checkout_url), and the exclusion (free edits captions/music/swap_shot need no quote). When/when-not/alternatives are all covered.

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