Retrieve a plan

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered. The description adds nothing beyond that — no note on behavior for an unknown or malformed id, no indication of what a plan record comprises, and no environment/livemode caveats.

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?

It is short and front-loaded, but the second sentence is essentially a restatement of the first with the word "id" added. The duplication consumes half the text without advancing understanding.

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 single-parameter read tool with full schema coverage and rich annotations, the minimal description is close to sufficient. However, with no output schema, the agent gets no indication of what a retrieved plan contains (amount, interval, currency, active status), leaving a real gap.

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% and the sole parameter already documents the `plan_…` id format. The description repeats the same prefix hint without adding meaning such as whether ids are reusable across livemode/test or what happens on a non-plan id.

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 and resource ("Retrieve a plan") and narrows it to a lookup by id, which is clearly distinct from create_plan, list_plans, and update_plan by name alone. It stops short of explicitly contrasting itself with list_plans or get_subscription, so it is clear but not fully sibling-differentiated.

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?

There is no guidance on when to use this versus list_plans (to enumerate) or get_subscription (to resolve a subscription's plan). The only implied condition is that a plan id is known, which is restated from the schema rather than offered as usage guidance.

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