sw_add_user_to_group

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

With no annotations, the description must carry the burden of behavioral disclosure. It does not mention the confirm requirement (Must be true to proceed) or that without confirm the tool returns a preview. It also does not clarify any permissions, side effects, or whether the action is reversible. This is a significant gap for a mutating tool.

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?

Two sentences, no redundancy. Every clause adds value: the action, the parameter preference, the fallback method, and the pointer to a sibling tool. This is a model of concise, structured description.

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?

The tool has 6 parameters and no output schema or annotations. The description explains the core action well but omits the confirmation behavior and return flow (preview without confirm). While the schema partially covers this, the description itself leaves out critical execution context, making it merely adequate.

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 50%, so the description compensates meaningfully by explaining the two parameter combinations: user_id alone, or first_name + last_name + email. It also highlights that user_id is preferred, adding practical guidance beyond the schema's bare field descriptions.

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 verb ('Add') and resource ('user to a Splitwise group'), and distinguishes the two identification methods. It is immediately obvious what this tool does and it naturally contrasts with the sibling 'remove user from group'.

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?

It gives explicit guidance on when to use user_id versus first_name/last_name/email, and references sw_list_friends as a helper to resolve names. It does not explicitly state when not to use this tool or mention alternatives like sw_create_friend, but the provided context is clear and actionable.

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