Intervals.icu MCP Server

create_custom_item

Create custom training metrics, charts, or fields for an athlete on Intervals.icu. Define item type, configuration, and visibility to extend athlete data analysis.

Instructions

Create a new custom item for an athlete on Intervals.icu

Args: name: Name of the custom item item_type: Type of custom item (e.g. FITNESS_CHART, TRACE_CHART, INPUT_FIELD, ACTIVITY_FIELD, INTERVAL_FIELD, ACTIVITY_STREAM, ACTIVITY_CHART, ACTIVITY_HISTOGRAM, ACTIVITY_HEATMAP, ACTIVITY_MAP, ACTIVITY_PANEL, ZONES) athlete_id: The Intervals.icu athlete ID (optional, will use ATHLETE_ID from .env if not provided) api_key: The Intervals.icu API key (optional, will use API_KEY from .env if not provided) description: Description of the custom item (optional) content: Configuration content for the custom item as a dict (optional). Important enum values: - "type" field for INPUT_FIELD/ACTIVITY_FIELD: must be "numeric", "text", or "select" (NOT "number") - "aggregate" field: must be "MIN", "SUM", "MAX", or "AVERAGE" (NOT "AVG") visibility: Visibility setting: PRIVATE, FOLLOWERS, or PUBLIC (optional)

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": {
      "name": "<name>",
      "item_type": "<item_type>"
    },
    "name": "create_custom_item"
  }
}

Input Schema

Name	Required	Description	Default
`name`	Yes
`api_key`	No
`content`	No
`item_type`	Yes
`athlete_id`	No
`visibility`	No
`description`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 6, 2026

TDQS

B3.3/5.0

Behavior2/5

Does 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 states the create side effect and mentions auth fallback via athlete_id/api_key, but it does not disclose constraints, duplicate-name behavior, required permissions, or any failure/validation traits. This is thin for a mutating tool.

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

Conciseness3/5

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

The one-sentence purpose followed by a compact Args list is well structured and front-loaded. But the corrupted content line undermines the clarity, and the list could be tightened without losing information.

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 7-parameter create tool with an output schema, the description covers all parameter names and several enums, so basic invocation is possible. It is not complete for more complex item types because the required shape of the content dict is under-specified and no guidance addresses conditional requirements.

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?

With 0% schema description coverage, the description compensates by listing every parameter and adding value: item_type examples, visibility options, env-var fallback for auth, and note that content is a dict. However, the content configuration details are incomplete and the allowed 'type' bullet is garbled/self-contradictory, so it only partially compensates.

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 opening sentence uses a specific verb and resource: create a new custom item for an athlete on Intervals.icu. The word 'new' clearly distinguishes it from the update_custom_item, get_custom_items, and delete_custom_item siblings without needing to inspect their schemas.

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?

The action is clear but there is no explicit when-to-use guidance or mention of alternatives. An agent can infer that it should be used for creating rather than updating or deleting, but the description relies entirely on that implication.

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