whmcs_send_emailSend targeted emails to clients in WHMCS using predefined templates or custom subject and message, with a related ID for client, invoice, or other records.
Send an email to a client
| Name | Required | Description | Default |
|---|---|---|---|
| id | No | Related ID (client, invoice, etc.) | |
| customtype | No | Custom type | |
| messagename | No | Email template name | |
| custommessage | No | Custom message | |
| customsubject | No | Custom subject |
Changes observed during successful MCP inspections.
v1.2.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must disclose behavioral traits. It only says 'Send an email' but does not explain if it queues the email, requires specific permissions, or side effects like triggering automation. For a mutation tool, this is insufficient.
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 only one sentence, but it is under-specified. Conciseness is not just brevity; effective communication is missing. Important context is omitted, making it too sparse.
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?
With 5 parameters and no output schema, the description should provide context on how parameters interact, constraints, and expected behavior. The single sentence fails to cover these, leaving the agent underinformed.
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 input schema has 100% description coverage, so the description adds no extra meaning beyond schema. Baseline score of 3 is appropriate as the schema already documents parameters, though the description could clarify parameter relationships.
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 'Send an email to a client' clearly states the verb and resource. Among sibling tools, there is no other tool with 'send email' purpose, though 'whmcs_get_email_templates' retrieves templates. The purpose is clear and distinguishable.
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?
No guidance on when to use this tool versus alternatives, prerequisites, or exclusions. The description lacks context like when to use customtype vs messagename, or that id must correspond to a valid record.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.