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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed-world scope, so safety and idempotency are covered structurally. The description's only added behavioral detail is that the response carries the template's EmailContent JSON, which is useful given there is no output schema, but it says nothing about error behavior for unknown IDs.

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?

A single front-loaded sentence naming the verb, the resource, the lookup key and the payload of interest, with 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?

For a simple two-parameter read with no output schema, the description covers the identity of the resource and what the response contains (EmailContent JSON). Only the failure mode for a missing ID is unaddressed, a minor gap.

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%, with templateId documented as 'Template ID (slug)' and apiKey's override behavior spelled out, so the schema carries the semantics. The description's 'by ID' merely echoes the schema rather than adding format or lookup guidance, making the baseline 3 correct.

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 ('Get') and resource ('a single starter template by ID') and implies the single-vs-list distinction against list_templates via 'single' and 'by ID'. It does not explicitly name any sibling, so it stops short of the top score.

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: 'by ID' suggests it is the follow-up to a list or search call, but the description never says when to choose this over list_templates or render_email_content, nor does it state any prerequisite such as knowing the template ID in advance.

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