update_custom_item

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

With no annotations, the description carries the behavioral burden. It discloses optional auth defaults from .env and important enum constraints for content fields, but does not state whether the update is partial or full replacement, what happens to unspecified fields, or what the response indicates. This is partial transparency.

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 purpose statement is front-loaded, followed by a structured Args list. The content is detailed but not redundant, though it could trim some obvious parameter names; overall it is well organized and every sentence adds value.

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?

Given 8 parameters, no schema descriptions, and no annotations, the description covers all parameters and key constraints. It omits explicit update semantics but the presence of an output schema reduces the need to document return values, so this is nearly complete.

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 meaning of all 8 parameters, including the item_id, optional athlete_id/api_key fallback behavior, and the required enum values for content.type and content.aggregate, adding value beyond the bare schema.

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 starts with a specific action and resource: 'Update an existing custom item for an athlete on Intervals.icu.' This clearly distinguishes it from sibling tools like create_custom_item, delete_custom_item, and get_custom_item_by_id.

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 implies usage through the verb 'Update' and lists optional fields, but it does not explicitly state when to prefer this over create_custom_item or delete_custom_item, nor mention any preconditions such as the item needing to exist.

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