send_message_to_group

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

There are no annotations, so the description carries the full burden. It discloses the return value format ('Mensagem enviada com sucesso' or 'Erro ao enviar mensagem...') and lists possible error conditions (group not found, connection, authentication, invalid message). It does not mention rate limits or idempotency, but for a send-message tool this is adequate behavioral context.

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 well-structured with purpose, Args, Returns, and Raises sections. It is front-loaded with the main purpose. However, it contains some redundancy (e.g., 'Esta ferramenta permite...' repeats the first sentence) and the Returns/Raises sections may be unnecessary if the output schema already covers them. Still, it is appropriately sized and each section adds value.

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 and the lack of annotations or schema descriptions, the description covers the essential aspects: purpose, parameters, return values, and error cases. It also provides a cross-reference to get_groups() for obtaining the group_id. It does not mention prerequisites like authentication, but it lists authentication failure as an error, implying auth is needed. Overall, it is complete enough for an agent to select and invoke the tool.

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 schema provides zero descriptions for the parameters, and the description fully compensates. It explains group_id's format ('XXXXXXXXXXXXXXXXX@g.us') and how to obtain it via get_groups(), and it details message content possibilities including formatted text, emojis, and line breaks. This adds significant meaning beyond the bare schema.

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: 'Envia uma mensagem de texto para um grupo específico do WhatsApp' (sends a text message to a specific WhatsApp group). It uses a specific verb and resource, and distinguishes itself from sibling tools like send_message_to_phone and get_groups by focusing on group messaging and referencing the group_id format.

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 provides usage context by explaining that group_id can be obtained via the get_groups() tool, guiding the agent on the prerequisite step. It implicitly differentiates from send_message_to_phone by targeting groups, but it does not explicitly state 'use this only for groups, not phones,' so there is no clear exclusion.

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