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

With no annotations, the description carries full responsibility and does well: it identifies a mutating operation, explains how null caps are represented/cleared, discloses that renaming does not destroy patron redemption rows, and flags operator-only access. These are exactly the side effects and auth requirements an agent must know.

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 short paragraphs front-load the purpose, then give the most important usage caveats in order of operational impact. No filler; each sentence earns its place.

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?

Given an output schema exists and this is a PATCH tool, the description covers the non-obvious semantics: clear flags, rename safety, and operator proof. Minor gaps remain around date formatting and numeric constraints, but overall an agent can call this tool correctly.

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%, and the description compensates for the trickiest fields: the clear_* flags and the partial-patch null convention. However, it leaves several parameter details to inference: date/time format for valid_from/valid_until, bounds for discount_percent, and the exact meaning of total_uses/uses_per_patron.

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 opens with 'Patch a coupon's editable fields,' a specific verb and resource that clearly distinguishes this from sibling tools like roastify_mint_coupon, roastify_delete_coupon, and roastify_redeem_coupon. 'Pass only the fields you want to change' reinforces PATCH semantics.

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 gives actionable how-to guidance: partial-field patching, using clear_uses_per_patron/clear_total_uses for unlimited caps, and notes that renaming the code preserves redemption rows. It does not explicitly contrast every sibling, but the context is clear enough for selection.

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