Preview a service template

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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavior beyond that: it is a dry-run that does not write the registry and it reports 'what already exists' as well as what would be created — a diff-style output hint the annotations do not 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?

Two tight sentences, front-loaded with the operation and its non-destructive scope, followed by the routing advice. No filler.

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 a full output schema (return values need not be described), complete annotations for safety, and 100% parameter coverage, the description supplies everything else an agent needs: the dry-run semantics, the pre-apply sequencing, and the fact that existing resources are reported.

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% and there is only one required parameter, so the schema already documents 'name' and its source ('from template_list'). The description adds no format, validation, or resolution detail, and its phrase 'built-in template' slightly nudges toward a different notion of the parameter than the schema's list-sourced name; baseline 3 applies.

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 ('Preview') and a precise resource ('which services a built-in template would create'), plus the key scoping fact 'without writing the registry'. This immediately separates it from template_apply (which writes) and template_list (which enumerates templates).

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?

Gives an explicit trigger: 'Use this before template_apply so the user can see what will be created.' The alternative tool is named and the sequencing condition is clear. There is no explicit when-not guidance (e.g., after the registry already matches), 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.