mcp-whatsapp

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

Annotations indicate this is a destructive, non-idempotent, open-world operation, and the description adds context by clarifying it's for joining groups via invites. However, it doesn't detail potential side effects like group notifications or permission requirements beyond what annotations imply.

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 a single, efficient sentence that front-loads the core action ('Join a group') and specifies the input format without any redundant information, making it highly concise and well-structured.

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 destructive tool with no output schema, the description adequately covers the purpose and input, but lacks details on behavioral outcomes (e.g., what happens on success/failure) or integration with sibling tools, leaving some contextual gaps despite good annotations.

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 description coverage is 100%, fully documenting the single parameter. The description adds minimal value by restating the parameter's purpose ('full invite URL or the bare invite code'), aligning with the schema but not providing additional semantics like format examples or edge cases.

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 specific action ('Join a group') and the required resource ('via a full chat.whatsapp.com invite URL or the bare invite code'), distinguishing it from sibling tools like 'create_group' or 'leave_group' which perform different operations on groups.

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 usage context by specifying the input format (invite URL or code), but does not explicitly state when to use this tool versus alternatives like 'create_group' for new groups or provide any exclusions or prerequisites for joining groups.

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