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

Annotations already declare readOnly=false, destructive=false, openWorld=true; the description adds genuinely new context: the HTML is encoded before submission, Mail Blaze enforces an unsubscribe link, and no email is dispatched. Missing only an idempotency/duplicate-name note against the idempotentHint=false annotation.

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 compact clauses with the 'WRITE:' prefix front-loaded as an operation-type signal. Every sentence carries information; nothing is redundant.

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 2-parameter mutation tool with annotations but no output schema, the description covers the write semantics and a key validation constraint. It could say more about what the response contains (e.g., the new template id) and about the 'name' field, but it is sufficient to invoke correctly.

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 50%; the description compensates for the html parameter by reiterating the unsubscribe-link requirement and disclosing the base64 transformation (useful, schema-invisible behavior). The required 'name' parameter gets no semantic elaboration in either place, leaving a real gap.

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 and resource ('create an email template from HTML') and adds a mechanism detail (server-side base64 encoding). It is distinguishable from get_template/list_templates by the 'create' verb, though it doesn't explicitly name a sibling to route away from.

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?

'Sends nothing' implies this is a preparatory step rather than a send action, which loosely separates it from send_transactional_email or create_campaign. However, there is no explicit 'use X when you want to actually send' guidance or prerequisite statement.

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