When to Use This Skill
Use this skill when you need to:
- Create new custom objects
- Generate custom object metadata XML
- Configure object sharing and security settings
- Set up object features and capabilities
- Troubleshoot deployment errors related to custom objects
- Add, update, or delete a field OR a validation rule on an existing object — any of these may make the object's stale, so you must refresh it (propose + confirm). This applies equally to validation-rule changes, not just fields. See Section 3.B.
Specification
1. Overview and Purpose
This document defines the mandatory constraints for generating CustomObject metadata XML (
file). The agent must verify these constraints before outputting XML to prevent Metadata API deployment errors.
🔔 Description freshness — applies to EVERY object change, fields AND validation rules: Whenever you add, update, or delete a field
or a validation rule on an object, the
may now be stale. Before finishing, refresh it per
Section 3.B (propose, confirm with the user, write). A validation-rule change counts exactly like a field change — the change is
not done until the description has been reconciled. This is easy to forget on validation-rule edits/deletes — don't.
2. Syntactic Essentials (Tier 1)
The following constraints must be true for the XML body to deploy successfully.
Note: The API Name (fullName) is NOT a tag; it is the filename (e.g.,
Vehicle__c.object-meta.xml
).
Required Elements
| Element | Requirement | Notes |
|---|
| Required | Singular UI name |
| Required | Plural UI name |
| Required | See Sharing Model Rules below |
| Required | Always set to |
| Required | Primary record identifier (requires and ) |
| Required | Always set to |
Sharing Model Rules
Exception: If this object contains a Master-Detail relationship field,
MUST be
.
Decision Logic:
- IF object has NO Master-Detail field → use
- IF object has Master-Detail field → use
- IF a Master-Detail field is being added to an existing child object → that existing object's must also be updated to
❌ INCORRECT — Will cause error:
Cannot set sharingModel to ReadWrite on a CustomObject with a MasterDetail relationship field
xml
<CustomObject xmlns="http://soap.sforce.com/2006/04/metadata">
<label>Order Line Item</label>
<pluralLabel>Order Line Items</pluralLabel>
<sharingModel>ReadWrite</sharingModel> <!-- WRONG: Object has a M-D field -->
<deploymentStatus>Deployed</deploymentStatus>
</CustomObject>
✅ CORRECT:
xml
<CustomObject xmlns="http://soap.sforce.com/2006/04/metadata">
<label>Order Line Item</label>
<pluralLabel>Order Line Items</pluralLabel>
<sharingModel>ControlledByParent</sharingModel> <!-- CORRECT -->
<deploymentStatus>Deployed</deploymentStatus>
</CustomObject>
3. Smart Defaults & Decision Logic (Tier 2)
The agent must choose which features to enable based on the object's intended use case.
A. The Name Field Decision
| Type | When to Use | Additional Requirements |
|---|
| Text | Default for human-named entities (Projects, Locations, Teams) | None |
| AutoNumber | Use for transactions, logs, or IDs (Invoices, Requests, Tickets) | Must include (e.g., ) and <startingNumber>1</startingNumber>
|
Text Name Field Example:
xml
<nameField>
<label>Project Name</label>
<type>Text</type>
</nameField>
AutoNumber Name Field Example:
xml
<nameField>
<label>Invoice Number</label>
<type>AutoNumber</type>
<displayFormat>INV-{0000}</displayFormat>
<startingNumber>1</startingNumber>
</nameField>
B. Object Description (Enrichment)
:
Mandatory — every Custom Object MUST have one. It must read like human-written documentation,
never a generic template ("Object used to track and manage...") or a metadata dump ("Contains 8 fields including
...").
Always compose an enriched description — when creating the object, and again on any change to it: adding, updating, or deleting a field or a validation rule (so it never goes stale). The change — field or validation rule — is never "done" until you've refreshed the object's description. This is not optional; do not ask whether to add a description.
Confirm per change — every time. Propose and confirm on each field/rule change separately. A previous "keep current" applies only to that one change; it is never standing permission to skip the proposal on a later change. Do not infer a preference from an earlier answer — re-propose and re-ask for every new change.
Compose the description (steps below). If the object already has one, use it as a strong signal — preserve the business context it carries (domain, team, intent the schema can't reveal) and fold the new field/rule in rather than discarding it.
Then branch on whether a description already exists:
-
No existing description (brand-new object): there is nothing to overwrite — just write the composed description. Do not prompt.
-
An existing description (update, delete, or any re-enrichment): never overwrite it silently — you can't tell from the file whether it was hand-written by an admin or generated earlier. Show the proposal, ask, and STOP — wait for the user's reply before writing:
Proposed description for
:
<the enriched description>
Current:
<the existing description>
Use this? (yes / keep current / edit)
You MUST NOT write the until the user replies — showing the diff is not approval, even when the change looks obvious or minor. Then act:
yes → write the proposed text ·
keep current → leave the existing one untouched (this applies to
this change only — re-propose on the next one) ·
edit → use the user's wording.
Always end with a
written.
Composing the description:
- Classify each field by how it appears in the description:
- Constrained (required, unique, externalId, restricted picklist) → selective parenthetical:
VIN (required, external ID)
,
- Behavioral (formula, roll-up) → describe what it computes: "the Age Years field auto-calculates vehicle age"
- Relationship (master-detail, lookup) → woven context: "as a child of Account" (never "(Master-Detail to Account)")
- Standard → label only
- Compose in this order, using field labels not API names:
Purpose → key fields → computed fields → validation rules (as business rules) → "Commonly used for {use cases}."
- Count and trim before writing (required): count the words; aim ~45, hard ceiling 50. If over, tighten wording first, then drop whole sentences in priority order (use cases → rules → computed; never drop sentences 1–2). Recount. Do not write until ≤ 50.
Example (Car, 46 words):
xml
<description>The Car object tracks vehicle inventory and maintenance. It captures Year, VIN (required, external ID), Color (Red/Green only), and Location; the Age Years field auto-calculates vehicle age. VIN is required and Black cars cannot be sold. Commonly used for fleet management, inventory tracking, and service scheduling.</description>
→ For the full workflow and examples, read
references/description-enrichment.md
.
C. Junction Object Naming
If the object is a many-to-many link between two parents, name the object by combining the two parent entities to ensure the schema remains intuitive.
Examples:
- (links Position and Candidate)
- (links Job and Application)
D. Feature Enablement (Clean XML)
To maintain "Clean XML," only include optional tags when deviating from the Salesforce platform default of
.
Scenario A: User-Facing Objects (Apps, Trackers, Business Entities)
- Trigger: The object is intended for direct user interaction
- Action: Set , , , and to
Scenario B: System-Facing Objects (Junctions, Background Logs)
- Trigger: The object exists for technical associations or background data
- Action: Omit these tags to keep the UI clean and the XML lean
4. Critical Constraints & Common Failures
Reserved Words
Never use reserved words as API names for Custom Objects or Custom Fields:
| Category | Reserved Words (Do Not Use as API Names) |
|---|
| SOQL/SQL | , , , , , |
| System | , , , |
| Temporal | , |
Relationship Cap
Do not create more than 2 Master-Detail relationships for a single object. If a third relationship is required, use a Lookup instead.
XML Root Element
Do NOT include the
tag at the root of the
file. The API name is derived from the filename.
❌ INCORRECT:
xml
<CustomObject xmlns="http://soap.sforce.com/2006/04/metadata">
<fullName>Vehicle__c</fullName> <!-- WRONG: Remove this -->
<label>Vehicle</label>
</CustomObject>
✅ CORRECT:
xml
<CustomObject xmlns="http://soap.sforce.com/2006/04/metadata">
<label>Vehicle</label>
<!-- fullName comes from filename: Vehicle__c.object-meta.xml -->
</CustomObject>
Validation Rule Naming Convention
Validation rule names follow different conventions than custom fields.
Rules:
- Must contain only alphanumeric characters and underscores
- Must begin with a letter
- Cannot end with an underscore
- Cannot contain two consecutive underscores
- Must NOT end with (unlike custom fields)
❌ INCORRECT:
xml
<validationRules>
<fullName>Require_Start_Date__c</fullName> <!-- WRONG: Has __c suffix -->
<active>true</active>
<errorMessage>Start Date is required.</errorMessage>
<formula>ISBLANK(Start_Date__c)</formula>
</validationRules>
Error: The validation name can only contain alphanumeric characters, must begin with a letter, cannot end with an underscore...
✅ CORRECT:
xml
<validationRules>
<fullName>Require_Start_Date</fullName> <!-- CORRECT: No __c suffix -->
<active>true</active>
<errorMessage>Start Date is required.</errorMessage>
<formula>ISBLANK(Start_Date__c)</formula>
</validationRules>
Naming Pattern Reference:
| Metadata Type | Naming Pattern | Example |
|---|
| Custom Fields | Ends with | |
| Validation Rules | No suffix | |
| Custom Objects | Ends with | |
5. Verification Checklist
Before generating the Custom Object XML, verify:
Syntactic Checks
Sharing Model Check (Critical)
Constraint Checks
Validation Rule Checks (if applicable)
Description Enrichment Quality Checks
Architectural Checks
Reference File Index
| File | When to read |
|---|
references/description-enrichment.md
| Composing or refreshing an object's (on create, or when a field/rule changes) — full enrichment workflow, field-prioritization tiers, junction/child handling, edge cases, and more examples |