Criar personagem no Flow

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

Adds substantial behavior beyond annotations: the portrait is generated by Nano Banana at 0 credits, appears in the chat, corpo costs ~25 extra seconds, and a partial failure returns an ATENÇÃO block with the created name and page link. That failure-mode contract is exactly the kind of context annotations (readOnly=false, destructive=false, openWorld=true) cannot convey.

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 purpose, then invocation, then failure recovery, then downstream usage — a sensible order. It is dense and slightly over-stuffed (credit pricing tied to 'out/2026', provider name) for a tool description, which keeps it from a 5.

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?

No output schema, and the description compensates by describing what the agent gets back (portrait in the chat, ATENÇÃO block on partial failure with name and link) and how to reference the character later. For a 7-parameter creation tool with open-world behavior, nothing essential to correct invocation is missing.

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 coverage is 100%, so baseline is 3; the description still adds value by spelling out the descricao/imagem either-or decision and the appearance facets the descricao should cover (espécie/rosto, cabelo, roupa, estilo), plus that corpo also triggers a full-body image. It does not go deeper on projeto or voz than the schema already does, so 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 ('Cria um personagem do Google Flow') plus the scope that distinguishes it: a reusable asset for 'vários vídeos e imagens com a mesma aparência (e voz)'. It names the sibling it is not (flow_personagem_editar) and the downstream tools, so an agent can differentiate it from flow_personagem_editar/excluir without opening schemas.

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 the two mutually exclusive input paths explicitly ('Informe nome e descricao ... OU uma imagem'), lists optional fields, and states the failure-handling alternative: correct with flow_personagem_editar (nome: the link) 'em vez de criar de novo'. It also tells the agent how to consume the result ('Depois use personagens: [nome] em flow_gerar_video / flow_gerar_imagem').

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