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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description confirms 'free and read-only' and adds genuinely useful boundary context by stating that analysis numbers and findings exist only in the paid study, plus that price/purchase info is included. This is real behavioral detail beyond the 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?

The main sentence is front-loaded with verb, resource, and return contents, and every clause about the free/paid split earns its place. The trailing Spanish sentence is a light duplication but reasonable for a bilingual toolset.

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 usefully enumerates the returned fields (methodology, sample, models, question-universe, index, price), substituting for a missing return spec. Combined with the read-only annotation, an agent has enough to call it correctly, though the paid/free boundary of the index of analyses could be spelled out more precisely.

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 id parameter and its valid values ('metricas', 'como-comprar', study slug) are already fully documented in the schema. The description only restates that the id comes from search, adding marginal value, so the baseline of 3 applies.

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 ('Returns the free sheet of a study by id') and enumerates the exact sections returned, which is far more informative than a tautology. It is not fully distinguished from the near-synonymous sibling ver_ficha, so the agent may still hesitate between the two.

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 parenthetical 'id (from search)' implies the id originates from the search/buscar_estudios flow, giving implicit usage context. However, there is no explicit when-to-use guidance or differentiation from siblings like ver_ficha, ver_metricas, or como_comprar.

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