Purelymail MCP

Create routing rule

create_routing_rule

Create a domain routing rule that matches a local-part user (optionally as a prefix) and reroutes mail to specified target addresses; each user/prefix must be unique per domain.

Instructions

Creates a routing rule for a domain. It must not have the same user/prefix as another rule on that domain.

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": {
      "domainName": "<domainName>",
      "prefix": "<prefix>",
      "matchUser": "<matchUser>",
      "targetAddresses": "<targetAddresses>"
    },
    "name": "create_routing_rule"
  }
}

Input Schema

Name	Required	Description
`prefix`	Yes	Whether matchUser is matched as a prefix of the local part
`catchall`	No	Whether this rule will not fire if the address maps to a user. Defaults to false.
`matchUser`	Yes	Local part to match, i.e. "user" in "user@domain.org"
`domainName`	Yes
`targetAddresses`	Yes	Full email addresses this mail will be rerouted to

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.1Nov 13, 2026

TDQS

B3.4/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the mutation profile is covered structurally. The description usefully discloses a failure mode (duplicate user/prefix rejection) that annotations cannot express, but it says nothing about required permissions, domain-existence prerequisites, or what is returned on success.

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

Conciseness4/5

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

Two sentences, front-loaded with the action and followed by the constraint; no filler. The uniqueness clause is slightly compressed ("user/prefix") but still parses cleanly against the schema's matchUser and prefix fields.

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 5-parameter write tool with no output schema, the description covers purpose and one precondition but omits permissions, domain-existence requirements, and any indication of the created rule's identifiers in the response. Adequate to invoke, not complete enough to predict outcomes confidently.

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

Parameters3/5

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

Schema description coverage is 80%, so the schema already explains matchUser, prefix, targetAddresses and catchall. The description's reference to the "user/prefix" pair reinforces how matchUser and prefix combine as a uniqueness key, which is a modest addition beyond the schema rather than a substantive one.

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?

The description uses a specific verb and resource ("Creates a routing rule for a domain") and adds a uniqueness constraint on the user/prefix pair, so the agent knows exactly what entity is being produced. It does not name or differentiate itself from siblings like list_routing_rules or delete_routing_rule, but the verb makes the distinction reasonably obvious.

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 by the create semantics and the stated precondition that no other rule on the domain may share the user/prefix. There is no explicit guidance on when to prefer this over update_domain_settings or how it relates to sibling routing tools, and no statement about the domain needing to exist first.

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