Add a person to an existing expense group by specifying the group ID and member name, enabling their participation in shared expense tracking and settlement.
Add a new member to an existing group.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | ||
| group_id | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It only says 'Add', implying a mutation, but discloses no other behavior: what happens if the member already exists, whether the operation is reversible, any side effects, or the return value. For a write operation with zero annotation coverage, this is a significant gap.
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 concise sentence with no redundant words. It is front-loaded and appropriately sized for the simplicity of the action, though it sacrifices informativeness for brevity.
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 simple 2-parameter tool, the description is incomplete. It does not mention that the group must already exist, that name is required and its format, or any error cases. Although an output schema exists, it is not shown, and the description provides no context about the result. The minimalism leaves an agent with insufficient information to call the tool correctly in varied scenarios.
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 has 0% description coverage, and the tool description does not mention either parameter. It does not explain that group_id must reference an existing group or that name is the new member's identifier. The description adds no meaning beyond the parameter names themselves, which is inadequate given the schema lacks 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 states a specific action: 'Add a new member' to an 'existing group'. The verb and resource are clear, and it naturally differentiates from sibling tools like create_group (which creates a new group) and get_group (which reads). No ambiguity about what the tool does.
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 only states the action without any guidance on when to use it versus alternatives. It does not mention prerequisites (e.g., group must exist), exclusions, or alternatives. An agent must infer that this is the right tool for adding members based on the name alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.