get_custom_items

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

With no annotations provided, the description carries the behavioral transparency burden. It does disclose that both parameters are optional and fall back to environment variables, which is useful. However, it does not mention response shape, whether a list is always returned, pagination, possible auth failures, or other runtime behavior. The read-only 'Get' verb is present but not explicitly framed as a safe operation.

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 well-structured: a single front-loaded purpose sentence followed by an Args block. No fluff or irrelevant detail. Every sentence serves a functional role, and the structure makes parameter behavior easy to scan.

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 the simple read-oriented nature of the tool and the presence of an output schema, the description covers the main invocation contract: what is retrieved, for whom, and how authentication is handled. The main missing piece is explicit routing to/from sibling tools, especially get_custom_item_by_id, and any caveats about empty results or auth errors. Overall it is close to complete for a straightforward list endpoint.

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. It clearly explains both parameters: athlete_id is the Intervals.icu athlete ID and api_key is the API key, and it notes that each falls back to a .env variable if omitted. This adds meaningful semantics beyond the bare schema and gives the agent enough to invoke the tool correctly.

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 states a clear verb and resource: 'Get custom items' with examples (charts, custom fields, zones) and the athlete scope. It doesn't explicitly distinguish from the sibling get_custom_item_by_id, but the plural 'items' and 'etc.' communicate a broader retrieval intent. This is more than a tautology and gives an agent a concrete sense of what the tool does.

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 guidance is given about when to prefer this tool over alternatives such as get_custom_item_by_id, create_custom_item, or update_custom_item. The description explains argument fallbacks but does not provide any when-to-use or when-not-to-use context. The agent is left to infer use cases from the name alone.

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