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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is covered. The description still adds real value beyond them: the confirmation step before delete, the coupling rule that email templates require a subject while SMS ones do not, and the pointer to custom_fields_list/mergeTags for substitution tokens. It does not state whether deletes are permanent or how errors surface, which keeps it out of 5 territory.

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 short clauses, front-loaded with the resource definition before the action list and the merge-tag note. The telegraphic style reads as note fragments rather than sentences, but nothing is padded and every clause carries information.

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 6-parameter, 3-action mutation tool with no output schema, the description covers the essentials an agent needs before calling: what a template is, the type/subject coupling, and the confirm-before-delete rule. Gaps remain around permanence of deletion and partial-update semantics, but nothing critical to correct invocation is absent.

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 67%, and the two enums (`type`, `action`) carry no descriptions in the schema at all. The description compensates by explaining the sms/email distinction and the email-implies-subject rule, and by naming the three actions. It stops short of noting that `subject` is ignored for SMS or that `id` is only meaningful for update/delete, though the schema covers the latter.

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 names the resource (saved message templates) and enumerates the supported verbs (create, update, delete), so the CRUD scope is unambiguous. The sibling templates_list exists for reads, and while the description implies it by listing only mutating actions, it never names the sibling explicitly.

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?

There is one concrete usage instruction — 'delete (confirm first)' — which sets a workflow precondition for the destructive path. Beyond that, the description does not say when to reach for this tool versus templates_list or how update differs from create when fields are partially supplied; guidance is implied rather than stated.

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