get_custom_item_by_id

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

With no annotations provided, the description carries the burden of behavior disclosure. 'Get' implies a read-only operation, and the Args section usefully explains that athlete_id and api_key fall back to environment variables. However, it does not explicitly state side-effect safety, error behavior, or any API-specific constraints.

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 concise and front-loaded: a clear one-line purpose is followed by a compact Args list. No filler or redundant content is present, and every sentence contributes useful 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 simple read operation with an output schema, the description is sufficiently complete. It identifies the source system, required and optional parameters, and the auth fallback strategy. Since an output schema exists, not explaining return values is acceptable.

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%, but the description compensates by documenting all three parameters: item_id as the target ID, and athlete_id/api_key as optional credentials with explicit .env fallback behavior. This adds meaning beyond the raw schema by clarifying default resolution and optionality.

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 clearly states the verb 'Get', the resource ('detailed information for a specific custom item'), and the source system ('Intervals.icu'). The singular 'specific' distinguishes it from the sibling get_custom_items, which is best interpreted as a list operation.

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?

No explicit guidance is provided about when to use this tool instead of alternatives such as get_custom_items, get_activity_details, or get_event_by_id. The only selection hint is the phrase 'specific custom item' plus the tool name itself, which leaves usage context implicit.

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