Add a new tag to Radarr for organizing and filtering movies. Assign labels to titles to simplify searches and manage library categories.
Create Tag.
POST /api/v3/tag
Args: body: Request payload. Read the matching GET or the /schema endpoint first to see the fields this resource expects.
| Name | Required | Description | Default |
|---|---|---|---|
| body | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already flag this as a mutating, idempotent, non-destructive operation; the description adds only the HTTP verb and a payload-discovery instruction, not deeper behavioral context such as auth requirements or error/side-effect behavior. It does not contradict the annotations, but it contributes little beyond them.
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 compact and front-loaded: operation, endpoint, and the single argument are each stated in a few short lines. Every sentence serves a purpose, and there is no redundant filler.
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?
Because the body schema is opaque, the description's instruction to first read a GET or /schema endpoint is essential and partially fills the gap. It remains vague about which matching GET is intended and gives no tag-specific shape or required-field information, so an agent must still do extra discovery before invoking the tool correctly.
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?
With one opaque `body` object (additionalProperties true) and 0% schema description coverage, the description wisely tells the agent to read the matching GET or /schema endpoint to learn the expected fields, which is an actionable discovery path. It still gives no concrete tag fields or constraints, so it only partially compensates for the schema's lack of information.
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 Tag', and includes the exact REST endpoint 'POST /api/v3/tag', so the basic operation is unambiguous. It does not explain what a tag is nor explicitly contrast it with sibling tools like create_autotagging, update_tag_by_id, and list_tag, which prevents a 5.
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 operation itself gives an implied usage: use this tool when creating a tag. The description also provides one concrete prerequisite, to read a matching GET or /schema endpoint before supplying the body, but it never states when not to use this tool or how it compares with related tag/autotagging operations.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.