Read AlzaSubscription overview

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

Annotations already carry readOnly/idempotent hints, and the description reinforces read-only. It adds critical behavior beyond annotations: the `action` must come from a server-provided subscriptionAction via account menu or authenticated navigation and must be passed verbatim, never hand-crafted. This materially changes how the agent should invoke the tool.

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?

Four short sentences, each earning its place: what is being read, when to use it, how to pass the action, and that it is read-only. The most decision-relevant information is front-loaded.

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 one-parameter read tool with an output schema and readOnly/idempotent annotations, the description fully covers the action source, the intended pre-activation/update timing, and the rule against hand-crafting. Nothing call-critical appears missing.

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?

The input schema already documents the single `action` parameter at 100% coverage, including verbatim copying and `form.meta.href`. The description adds specificity about the origin of the action ('server-provided subscriptionAction from the account menu or authenticated navigation'), which helps an agent know where to obtain the value beyond the bare schema.

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: 'Read the AlzaSubscription overview (phases, savings, trial settings)' and explicitly ties its purpose to showing subscription state before the activation/update siblings. The description clearly distinguishes it from `subscription_activate` and `subscription_update_installment` by making it the read-side prerequisite.

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?

Provides explicit context: 'Use to show the user their subscription state before `subscription_activate` or `subscription_update_installment`.' It says when to use the tool, but does not explicitly state when not to use alternatives or name an alternative read tool, so it misses the full upper band.

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