group_join

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

With no annotations provided, the description carries full burden for behavioral disclosure. While it describes the basic action, it doesn't mention important behavioral aspects: whether this requires specific permissions, what happens on success/failure, if there are rate limits, or what the user experience will be. For a mutation tool with zero annotation coverage, this leaves significant gaps.

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 perfectly front-loaded with the core purpose in the first sentence, followed by parameter details in a clear 'Args:' section. Every sentence earns its place with no wasted words, making it efficient and easy to parse.

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 single-parameter mutation tool with no annotations and no output schema, the description covers the basic purpose and parameter semantics adequately. However, it lacks information about return values, error conditions, or behavioral constraints that would be important for complete understanding. It meets minimum viable standards but has clear gaps.

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 description coverage and only one parameter, the description fully compensates by providing essential semantic context. It explains what the 'code' parameter represents ('Invite code from a group link'), specifies the exact format ('the part after https://chat.whatsapp.com/'), and clarifies the source. This adds substantial value 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 specific action ('Join a WhatsApp group') and resource ('by invite code'), distinguishing it from sibling tools like group_leave, group_info, or group_rename. It provides a precise verb+resource combination that leaves no ambiguity about the tool's function.

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 invite code format ('the part after https://chat.whatsapp.com/'), but doesn't explicitly state when to use this tool versus alternatives like group_participants_add or when not to use it (e.g., if already in the group). It provides clear context but lacks explicit exclusions or alternative recommendations.

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