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

Discloses genuinely non-obvious behavior: the call has no live effect, it returns a preview plus a confirmation link, and only the merchant can activate it. This is consistent with destructiveHint=false (nothing harmful changes) and readOnlyHint=false (a pending routine object is created), so the apparent tension with "changes nothing" is reconcilable. Not a 5 because it omits any auth/scope context.

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?

Purpose is front-loaded and the sentences are short. However, "Money is integer minor units (cents)" earns no place here because routines_create has no monetary parameters, so one of four sentences is wasted.

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 correctly explains the return (a preview of what would change and a confirmation link) and the deferred-execution model. It is nearly complete; it could say more about what the preview contains or the account scope required.

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%, so the schema already documents all six parameters; baseline is 3. The description adds one useful hint for the prompt parameter ("nobody answers questions during a run"), but the money-units sentence refers to no parameter this tool actually has.

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 ("Set up a routine"), which an agent can map cleanly to the create operation. It does not, however, explicitly distinguish itself from the sibling routines_update/routines_list/routines_delete, so it lands at 4 rather than 5.

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 explains the workflow the call triggers (preview then merchant confirmation) but never states when to reach for this tool versus routines_update or routines_list, nor any prerequisite. Usage is only implied by the deferred-execution narrative, so 3.

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