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Mailercloud

by com.mailercloud.mcp
OverviewDiscussionsAdmin

update_template

DestructiveIdempotent

Update an existing HTML email template. Only the fields you pass change; the current name, HTML, plain text and category are kept otherwise. It can't change drag-and-drop templates: revise those with update_dnd_email_template, and design new ones with create_dnd_email_template. Personalise with [[key]] merge tags, e.g. [[name]] for the first name (keys from list_custom_fields); {{…}} is not replaced in campaigns. Templates that would send broken (raw or unknown tags, a tag after a greeting, http images, missing alt text, placeholder links, over 102 KB) are refused with the fixes.

Input Schema

NameRequiredDescriptionDefault
htmlNoNew HTML content (leave out to keep the current HTML)
nameNoNew template name (leave out to keep the current name)
dry_runNoShow what would change without changing anything
plain_textNoNew plain text (leave out to keep it; if only html changes it is regenerated from the new HTML)
category_idNoCategory ID from list_template_categories; 0 = uncategorized (leave out to keep the current category)
template_idYesTemplate ID

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • changedInput schema / properties / template_id / description
      Previous value: -"Template ID,required"New value: +"Template ID"
  2. Changed7 schema fields changed
    • addedInput schema / properties / category_id
      Added value: +{
+  "description": "Category ID from list_template_categories; 0 = uncategorized (leave out to keep the current category)",
+  "type": [
+    "null",
+    "integer"
+  ]
+}
    • changedInput schema / properties / html / description
      Previous value: -"HTML content"New value: +"New HTML content (leave out to keep the current HTML)"
    • changedInput schema / properties / html / type
      Previous value: -"string"New value: +[
+  "null",
+  "string"
+]
    • changedInput schema / properties / name / description
      Previous value: -"Template name"New value: +"New template name (leave out to keep the current name)"
    • changedInput schema / properties / name / type
      Previous value: -"string"New value: +[
+  "null",
+  "string"
+]
    • changedInput schema / properties / plain_text / description
      Previous value: -"Plain text content"New value: +"New plain text (leave out to keep it; if only html changes it is regenerated from the new HTML)"
    • changedInput schema / properties / plain_text / type
      Previous value: -"string"New value: +[
+  "null",
+  "string"
+]
  3. Changed2 schema fields changed
    • removedInput schema / properties / api_key
      Removed value: -{
-  "description": "MailerCloud API key",
-  "type": "string"
-}
    • addedInput schema / properties / dry_run
      Added value: +{
+  "description": "Show what would change without changing anything",
+  "type": "boolean"
+}
  4. First observed

TDQS

A4.6/5.0
Behavior4/5

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

Annotations already declare mutation (readOnlyHint=false), destructiveness and idempotency, but the description adds real substance: partial-update semantics ('only the fields you pass change'), the full set of validation rejections with the reason categories, and the promise that 'fixes' are returned. It stops short of saying what a failed update leaves behind or what the response contains, so it is strong but not exhaustive for a destructiveHint=true tool.

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?

It is front-loaded with the verb and the partial-update rule before alternatives and validation detail, and no sentence is filler. It is slightly dense — the merge-tag sentence carries a parenthetical, a cross-reference and a caveat at once — but nothing should be cut.

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

Completeness5/5

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

With 6 flat parameters, full schema coverage and no output schema, the description covers the remaining gaps an agent would have: partial-update behavior, template-type eligibility, merge-tag vocabulary, and the validation gate that can reject the call. Nothing essential to calling it correctly is missing.

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

Parameters4/5

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

Schema coverage is 100%, so per-field meanings are already documented and a baseline of 3 applies. The description still earns a bump by specifying the [[key]] merge-tag syntax accepted in the html payload and the fact that unknown/raw tags are refused, which is semantics an agent needs to construct a valid html value.

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

Purpose5/5

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

The description opens with a specific verb and resource ('Update an existing HTML email template') and immediately scopes it against the sibling family it does NOT handle by naming update_dnd_email_template and create_dnd_email_template. An agent can distinguish this from create_template, get_template and the DnD variants without opening any schema.

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

Usage Guidelines5/5

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

It explicitly routes away from the tool for drag-and-drop templates and names the correct alternatives for both revising and creating them. It also directs the agent to list_custom_fields for merge tag keys and warns that {{…}} is not substituted, which is exactly the guidance needed before invoking.

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

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