Change the state of a subscription (write)

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

With no annotations, the description carries the full burden and discloses key behaviors: WRITE, terminate is not immediate by default, upgrade terminates the current subscription and creates a new one, and customer rights change. It does not mention permissions or rate limits, but the side-effect disclosure is strong.

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?

Three sentences, first word signals write, then the core purpose, then critical caveats. Every sentence earns its place with no filler or redundancy.

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 complex 5-parameter mutation tool with no output schema and no annotations, the description covers the main behaviors, side effects, and follow-up actions. It does not detail the 'start' or 'suspend' behavior in depth, but the schema and enum fill some gaps, so it is slightly above adequate.

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% and every parameter already has a description. The text adds some meaning (immediate affects terminate, offer_ref is for upgrade, subscription_id comes from list_subscriptions), but this is modest value beyond the schema, matching the baseline.

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 clearly states a specific verb ('Moves') and resource ('an existing ProAbono subscription'), then enumerates the exact actions (upgrade, downgrade, start, suspend, terminate). It differentiates from siblings like create_subscription by specifying 'existing' and from list_subscriptions by being a write operation.

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 gives practical guidance: identify the subscription via list_subscriptions, and read customer rights with get_usages after an upgrade. It implies this tool is for existing subscriptions, but does not explicitly say when to prefer create_subscription or list the exclusions, so it stops short of a 5.

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