get_custom_item_by_id

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the '(read-only)' note merely restates the structured data. The description adds useful detail about the shape of the return (JSON content configuration with code, value type, units, options, aggregate), but says nothing about auth, errors, or resolution of the optional athlete default.

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?

Two compact lines that front-load the purpose before enumerating fields and the id source. Every sentence carries information, though the injected 'Ids: get_custom_items' fragment is slightly telegraphic rather than prose.

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?

With no output schema, the description carries the return-value burden and does so by listing which fields come back plus the JSON content configuration. Combined with full schema coverage and read-only annotations, an agent has what it needs; only error/empty-result behavior is unaddressed.

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 100%, so both item_id and athlete_id are already documented, including the default for athlete_id. The description only echoes the schema's pointer to get_custom_items for ids and adds no new parameter semantics, making the baseline 3 appropriate.

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 specific verb+resource ('full definition of one custom item') and enumerates the fields returned (name, type, description, visibility, index, content configuration). It distinguishes itself from the sibling get_custom_items by noting it retrieves a single item by id, though the plural-vs-singular distinction is conveyed mostly by the tool name.

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?

'Use for the full definition of one custom item' gives implied usage context, and 'Ids: get_custom_items' routes the agent to the sibling that supplies the required identifier. However, there is no explicit statement of when not to use it or what an alternative would be for related needs.

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