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

Annotations only cover the read-only/open-world safety profile, and the description adds substantial context beyond that: the tool is paid via x402 at 0.02 USDC on Base, and the behavior differs by payment state (without payment it returns payment requirements; with the base64 X-PAYMENT header it returns the analysis). That two-state contract is the critical thing an agent must know before calling and is not derivable from annotations.

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 return content, then usage, then exclusions, then the payment model — a logical order with no filler sentences. The opening enumeration of six facets is dense but each item maps to real output content, so it earns its space.

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?

With no output schema, the description carries the burden of describing return values and does so explicitly (per-facet analysis plus final and negative prompts). Payment cost, currency, chain, and the unauthenticated fallback behavior are all disclosed, leaving nothing an agent needs in order to call it 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 100%, so the baseline is 3, but the description adds the consequence of the 'payment' parameter — that omitting it yields a payment-requirements response rather than an error — which the schema does not state. It adds little about image_url beyond the schema, hence not a 5.

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 ('Devuelve el prompt que describe una imagen') and enumerates the exact facets returned (encuadre, gesto, direccion de luz, paleta, medio y camara, prompt final y negativo). It also sharply delimits what it is not ('NO recupera el prompt original ni regenera la imagen'), which separates it from siblings like variaciones_estilo or generate_composition.

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 clear when-to-use context ('Util para describir, remezclar o extender una imagen que no hiciste tu') plus explicit when-not-to-use exclusions (no prompt retrieval, no regeneration). It stops short of naming a specific alternative sibling to use instead for those excluded cases, so it is clear but not fully routing.

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