Add a new custom property with optional values by providing a unique name and either type ID or type name. Requires write access.
Create a Custom Property with optional values. Provide typeId OR typeName. Name: unique, ≤16 chars, no spaces. Values: unique, ≤32 chars each. Requires 'Write' on 'CustomProperty'.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | ||
| typeId | No | ||
| values | No | ||
| typeName | No |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. It discloses important behavioral requirements: Write permission on 'CustomProperty', uniqueness constraints, length limits, and the prohibition on spaces in names. It does not fully describe error behavior or what the response contains, but the core side effects and prerequisites are transparent.
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 three concise sentences with no filler. It front-loads the core purpose, then packs constraints and permission requirements efficiently. Every sentence adds necessary information.
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?
For a 4-parameter create operation with no output schema and no annotations, the description is largely complete: it covers required inputs, optional values, uniqueness/length constraints, and permission requirements. It could add what happens if both typeId and typeName are supplied or what the created object response looks like, but these are minor gaps given the clarity of the rest.
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?
Schema description coverage is 0%, so the description must compensate, and it does. It explains the typeId/typeName alternative, name uniqueness and format, and values uniqueness and length. It does not elaborate on the nested value object structure beyond the schema, but the critical selection and validation semantics are present.
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 opens with a specific verb and resource: 'Create a Custom Property.' It clearly distinguishes this creation tool from the many sibling operations like custom_properties_get_by_id, custom_properties_update, and custom_properties_delete. The mention of optional values and type selection further clarifies the tool's exact scope.
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?
The description gives clear practical context by stating 'Provide typeId OR typeName' and enumerating constraints for name and values. It does not explicitly name alternative tools or say when not to use this one, but the 'Create' verb and the sibling set make the primary use case unambiguous. The lack of explicit exclusion clauses keeps it just below a 5.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.