Add a member to an existing SignUpGenius group using their email address. Optionally include first and last names.
Add a member to a SignUpGenius group by email address. First/last name are optional. Writes data — confirm with the user before invoking.
| Name | Required | Description | Default |
|---|---|---|---|
| groupId | Yes | ||
| lastname | No | ||
| firstname | No | ||
| emailaddress | Yes | Email of the member to add to the group. |
Changes observed during successful MCP inspections.
v1.8.1Input schema / properties / emailaddress / patternPrevious value: -"^(?!\\.)(?!.*\\.\\.)([A-Za-z0-9_'+\\-\\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\\-]*\\.)+[A-Za-z]{2,}$"New value: +"^(?:[A-Za-z0-9_'+\\-]+\\.)*[A-Za-z0-9_'+\\-]*[A-Za-z0-9_+-]@(?:[A-Za-z0-9][A-Za-z0-9\\-]*\\.)+[A-Za-z]{2,}$"v1.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotation readOnlyHint=false already flags a write operation, and the description reinforces it with 'Writes data' while adding a confirmation requirement beyond the annotation. This is genuinely useful behavioral guidance for a mutating tool, though it does not cover side effects like duplicate-member behavior.
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?
Three short sentences with zero waste: the core action is front-loaded, parameter notes follow, and the write-caution closes. Every sentence earns its place.
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 add-operation with no output schema, the description covers the action, key parameters, and the confirmation gate. The only notable gaps are what the tool returns on success/failure and the semantics of groupId, both minor for this tool's complexity.
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 only 25% (only emailaddress is described), so the description must compensate. It adds that first/last name are optional and that membership is keyed by email, but the required-array already encodes optionality, and groupId receives no additional meaning in either the schema or the description.
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?
States a specific verb and resource: 'Add a member to a SignUpGenius group by email address.' The operation is distinct from all 19 siblings, which are predominantly read/list/report tools or slot-management tools; none perform group-member addition, so an agent can select this tool unambiguously.
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 when to use it (when adding a member by email) and adds a safety gate ('confirm with the user before invoking'), but it never names alternatives or states when not to use it. No explicit exclusions or comparison to sibling read tools are provided.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.