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

Annotations already declare non-readonly, non-idempotent, non-destructive, closed-world behavior, so the bar is lower. The description adds real value by disclosing the scoping ('for the connected user') and the return payload (project id plus editor link), which is important since there is no output 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?

Three short sentences, zero filler, front-loaded with the action and the when-to-use condition before the return description. Every sentence earns its place.

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 single-parameter creation tool with no output schema, the description covers the action, the trigger, and the return shape, which is what an agent needs. Minor gap: no pointer to the sibling that lists/searches templates for obtaining the slug.

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?

Only one parameter and schema description coverage is 100%, so the schema already defines 'slug'. The description restates it as 'a template slug' without adding format, discovery, or validation detail (e.g., where to obtain the slug), so it stays at the baseline.

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 (create), resource (letX project), actor (connected user), and source (template slug). The 'from a template slug' qualifier distinguishes it from the sibling create_project, which presumably creates a blank project.

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?

'Use when the user wants to start a document from a template' gives a clear triggering condition. It stops short of naming the alternatives (create_project for blank projects, search_templates/get_template for discovering slugs) or stating when not to use it.

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