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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower. The description adds useful behavior beyond annotations: archived templates are excluded by default, and publishedVersionId null means the template has never been published and cannot yet be sent by templateId. There is no contradiction.

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 sentences with no filler: endpoint, return fields, caveats, and sibling pointer are each given exactly one clause. The most decision-relevant information (what is listed and when archived templates appear) is front-loaded.

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 filtered list tool with readOnly/idempotent annotations, the description covers purpose, return fields, the one non-default flag, and the alternative for deeper content. No output schema exists, so the field enumeration and null semantics carry the necessary return-value explanation.

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 100%, so the baseline is 3 and the description does not need to compensate. It restates includeArchived's effect but adds no new meaning to either parameter beyond what the input schema already documents.

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 opens with a specific verb and resource ('List message templates') and names the exact endpoint plus the returned fields. It also distinguishes itself from get_template by delegating content and required params to that sibling, so an agent can tell the tools apart.

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?

It explicitly states that archived templates are hidden unless includeArchived is true, which tells the agent when to set that flag. It also gives an explicit alternative: 'Use get_template for content and required params,' covering the main when-not condition for this listing tool.

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