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

Annotations already mark this as a non-read-only, non-idempotent, non-destructive write. The description adds genuinely new behavior: consumers take the template 'by template_id and keep their own copy, so later edits to the template do not change them' – important copy-on-reference semantics an agent would not infer from the schema.

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 with the creation scope front-loaded and the propagation semantics second. No filler, though the second sentence is dense and could be split.

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?

No output schema and no annotations about permissions, so the description should carry more. The copy-on-reference behavior is well covered, but for a 6-parameter mutation tool it leaves the required body fields (html vs markdown) unexplained.

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 only 33%, and the description mentions almost no parameters beyond the implicit project association. It misses the critical rule that html and markdown are both required but exactly one should carry content, and adds nothing for name, subject or preview_text.

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 ('Save reusable email content') and scopes it to a project. It is clearly a creation tool and distinct from update_template/delete_template, though it never names those alternatives.

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 only implied: it explains that campaign steps, broadcasts and transactional emails consume templates, which suggests you create one before referencing it. There is no explicit when-to-use versus update_template or guidance on prerequisites such as an existing project_id.

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