addy-mcp

create_username

Add a new username to an addy.io account; each added username counts toward the plan's username limit.

Instructions

Create an additional username (counts against the plan's username limit).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "username": "<username>"
    },
    "name": "create_username"
  }
}

Input Schema

Name	Required	Description	Default
`username`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.2Nov 12, 2026

TDQS

A3.5/5.0

Behavior4/5

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

Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true). The description adds genuinely new behavioral context beyond them: the creation consumes a slot against the plan's username limit, which is a real cost an agent should know before invoking. It stops short of covering username format validation, duplicate handling, or error behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

One short sentence with the quota constraint front-loaded in the parenthetical. Nothing is wasted and the key consequence appears immediately.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter creation tool with annotations covering safety and no output schema, the definition is serviceable but thin. It omits the username format rules and what happens on collision or quota exhaustion, which are the details most likely to cause a failed or incorrect call.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% and there is one required parameter, so the description carries the burden of explaining the 'username' field. It only says a username is created, with no information on allowed characters, length, domain binding, or whether a domain must already exist. The single parameter's semantics are effectively undocumented.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: 'Create an additional username.' The parenthetical clarifies the quota implication, which helps an agent distinguish this from pure-read username tools like get_username. It does not explicitly contrast with create_alias, but the resource is unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied rather than stated: an agent can infer this is the tool for provisioning a new mailbox username, and the plan-limit note hints at a precondition for calling it. There is no explicit when-not-to-use guidance or reference to the sibling alternate tools for identity creation such as create_alias.

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

Deploy Server