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

Annotations already declare this is a non-read-only, non-idempotent, non-destructive write. The description adds a real precondition beyond that: the parent `grupo` must be a totalizer group. It does not describe auth requirements or whether a duplicate description causes an error, but the added constraint is genuine value.

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-loads the core purpose, then branches into the two modes in compact clauses; the examples ('2.01', 'Despesas Administrativas') are load-bearing. The nested parentheticals make it dense but nearly every token 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?

For a 7-param write tool with no output schema, the description covers mode selection, required vs optional fields, enum meanings, and a cross-reference to omie_list_category_types. The two undocumented params (`account`, `natureza`) are the remaining gap.

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?

With 0% schema coverage the description must carry the load, and it documents 5 of 7 params with meaning and mutual exclusivity: `descricao`, `grupo` (name OR code, with examples), `tipo_grupo` (R/D decoded), `tipo_categoria`, `codigo_dre`. It leaves `account` and `natureza` entirely unexplained, which keeps it out of the top band.

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+resource ('Cria uma categoria no plano de contas') and further distinguishes the two creation modes by their API operations (IncluirCategoria vs IncluirGrupoCategoria). An agent can differentiate this from omie_update_category and omie_get_category 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?

Gives explicit conditional rules for each mode: category requires `descricao` + `grupo`; new group requires `descricao` + `tipo_grupo` and no `grupo`. It also points to omie_list_category_types for the `tipo_categoria` value. It doesn't state when to prefer creating a group vs a category in business terms, so it falls short of a full 5.

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