Get Modelo 390 Summary (IVA Annual Recap)

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

Annotations already indicate readOnlyHint=true and idempotentHint=true, so the description adds minimal behavioral context beyond confirming it returns totals. It does not mention potential error conditions, authentication needs, or rate limits. The description adds value by describing return content but not behavioral traits 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?

The description is two concise sentences in English followed by a bilingual Spanish repetition. Every sentence serves a purpose: defining the tool, specifying outputs, and providing an example. No superfluous words. The most important information comes first.

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 the tool's simplicity (one optional parameter, no enums, output schema exists) and the richness of annotations and schema, the description covers the essential aspects. It explains the purpose, return values, and parameter usage. No significant gaps; the example aids understanding. The presence of an output schema compensates for any missing detail on return format.

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 input schema already covers the 'period' parameter with a description and format. The description adds an explicit example ('period='2025'') and repeats the format in Spanish. This provides concrete usage guidance, raising the score above baseline 3. No other parameters exist.

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's function: getting the IVA annual summary for Modelo 390 filing in Spain. It specifies the returned data (full-year totals by rate, deductible IVA, annual balance) and includes an example with 'period'. This distinguishes it from similar annual models (like Modelo 180, 347, etc.) by naming 'Modelo 390' and 'annual'.

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?

The description implies use for annual IVA summary through the term 'annual recap' and the example with a year. However, it does not explicitly state when to use this tool versus other modelo summaries (e.g., quarterly). No exclusion criteria or alternatives are mentioned, but the context of 'annual' provides sufficient guidance for a knowledgeable user.

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