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

Annotations only cover the read-only/idempotent safety profile; the description adds substantial context beyond them: the exact shape of the return, source citation with check dates, the requirement that the user signs in and confirms, and an explicit data-handling disclosure about what is stored from tool-call arguments. This is rich behavioral disclosure the annotations cannot convey.

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 usage trigger and dense with signal, but the final privacy/data-retention sentence is long and parenthetically overloaded, diluting the block. Every sentence does earn its place, so only mild trimming is warranted.

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?

With no output schema, the description carries the return-value burden and does so thoroughly, listing each element of the exit plan. Combined with the privacy note, the consent constraint, and the optional billing/renewal inputs, an agent has everything needed to call and set expectations.

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%, so the baseline is 3, but the description adds genuine meaning: billed_by is tied to 'the name on their card statement or receipt' and renewal_date is framed as yielding 'the last safe day to cancel'. That is semantic value beyond the schema's own descriptions.

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+resource (retrieve an exit plan for a named subscription) and enumerates the returned content in detail: cancel routes by biller, steps, notice periods, fees, refunds, export list. That scope statement is precise enough to separate it from siblings like search_exits or audit_stack 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?

Strong when-to-use trigger set with concrete example utterances ('cancel YouTube TV', 'how do I get out of Adobe') plus a hard behavioral constraint ('Never cancel for the user without their go-ahead'). However, it never names an alternative tool or a when-not condition, so the agent gets context but no explicit routing against siblings.

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