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

Annotations already flag destructiveHint=true, idempotentHint=false and openWorldHint=true, so the safety profile is covered. The description meaningfully adds patch-semantics ("fields you leave out keep their values"), which annotations don't convey. It omits, however, that supplying 'html' overwrites the entire body and that setting 'default' may unset other templates' defaults.

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 sentence, no waste, with the mutation and the merge behavior both front-loaded. It is a touch too terse for an 8-parameter mutation, but nothing is padded.

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 8 parameters, no output schema, and destructive annotations, the definition covers the merge contract but says nothing about the consequence of replacing 'html', how 'default' interacts with other templates, or what a successful response contains. Adequate but leaves real gaps for a destructive mutation.

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 75%, so the baseline is 3, but the description adds a semantic rule that applies to every optional parameter: omission preserves the existing value. That partial-update contract is not stated anywhere in the schema and is central to correct invocation.

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 ("Changes a tracking email template"), clearly distinguishing it from the create/delete/list_email_template siblings. It could be sharper about what 'tracking email' scope covers, but the action is unambiguous.

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 no explicit guidance on when to use this instead of create_email_template or update_tracking_email_settings, which is a genuinely close sibling. The partial-update note is behavioral, not usage selection, so an agent must infer applicability.

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