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

Beyond the readOnlyHint annotation, the description discloses the response shape ('Returns a HAL collection embedding fx:items') and the API contract. It does not explain HAL pagination semantics or zoom behavior, but the schema covers pagination parameters and readOnlyHint covers safety.

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 sentences, both informative: the first defines the resource, the second specifies return format and endpoint. No filler or redundant restatement of the title.

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?

Complete for a simple read-only list tool: the resource, response format, endpoint, and parameters are all covered. The readOnlyHint covers side-effect expectations, and no output schema is needed given the explicit HAL collection description.

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 coverage is 100%, so all four parameters are already documented. The description adds minimal parameter meaning beyond 'transaction_id' via the endpoint path and 'products purchased' context, but it does not need to compensate for schema gaps.

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?

States a specific verb ('List'), resource ('line items of a transaction'), and disambiguating parenthetical ('the products purchased'). It also provides the exact hAPI endpoint, making it clearly distinct from siblings like foxy_get_transaction and foxy_list_transactions.

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 makes the tool's scope clear: list items for a single transaction. It does not explicitly name alternate tools or state when not to use it, but the sibling list and endpoint path give sufficient context for an agent to route correctly.

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