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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), and the description adds real behavioral context: the postponed period is not prorated, trial end shifts with renewal date, next billing date changes, default per-call confirmation, and the Cotlet API key requirement. These are value-adding details an agent cannot get from the annotations alone.

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?

The first two sentences restate the same action ('Pause... until a date you set' / 'Pauses... until the renewal date you give'), which is wasted space. The remaining sentences (proration, trial, billing, confirmation, auth) each earn their place, so front-loading is fine but redundancy costs it.

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 2-required-parameter mutation tool with no output schema, the description covers the behavioral effects, the confirmation requirement, and the API key prerequisite, so an agent has enough to call it correctly. The main gap is the absence of explicit sibling routing, which is minor given the clear verb+resource.

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%, with renewal_date and subscription_id both documented in the schema itself. The description explains the effect of renewal_date behaviorally but adds no format, source, or constraint detail beyond the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

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 gives a specific verb and resource ('Pause an active subscription until a date you set'), making the pause semantics clear and distinguishable in spirit from cancel/change siblings. It stops short of naming the sibling tools it differs from, so an agent must infer the routing. Purpose itself is unambiguous.

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?

Usage is implied ('an active subscription', trial vs paid context) but there is no explicit when-to-use/when-not guidance or reference to alternatives like recurly_cancel_subscription or recurly_change_subscription. The confirm-before-each-call instruction is an operating rule, not tool-selection guidance. Adequate but leaves routing to inference.

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