apple_set_subscription_price

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

With no annotations, the description carries the full burden and does well: it discloses the external side effect, the ordering dependency on availability, per-territory issuance, and the concrete 409 failure mode with Apple's error text when the attribute is sent on an initial price. It stops short of auth/permission requirements and whether the change takes effect immediately or at a renewal boundary.

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?

Front-loaded with the core action, then prerequisites, then the parameter caveat; each sentence carries real information. The 'External action.' fragment is terse but useful. Slightly dense, but nothing is filler.

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 3-param mutation tool with an output schema, the description supplies the ordering prerequisite, parameter semantics, and the failure mode an agent will actually hit. The only gap is authentication/permission context, which is minor given the output schema covers the response.

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 0%, so the description must compensate, and it does for the two non-obvious parameters: the origin of price_point_id and the full semantics of preserve_current_price (only valid on a price change, None default omits the field entirely, 409 otherwise). subscription_id is left unexplained but is self-evident.

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 and resource ('Set the subscription price from a price point') and flags it as an external action. It names apple_list_price_points as the source of price_point_id, letting an agent distinguish it from siblings like apple_list_price_points or apple_set_free_price without opening a schema.

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?

Explicitly routes the agent: fetch price_point_id from apple_list_price_points and call it AFTER setting availability, since price points are issued per territory. It also states when preserve_current_price should and should not be sent. No meaningful usage condition is left to inference.

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