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

Annotations already declare readOnlyHint=true, and the description adds extra context: 'Free, no payment, no auth required,' which directly informs the agent about auth requirements and cost. It also details the return payload (HTML, CSS, sampleData, pageOptions), going beyond the minimal safety profile.

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 concise sentences: the first states the core action, the second gives usage guidance, and the third adds access information. No wasted words, front-loaded with the primary purpose.

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?

The tool is simple with one parameter and no output schema. The description fully compensates by enumerating the returned components and explaining exactly when and why to use it, making the tool self-contained and clear.

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?

The schema covers the single parameter 'slug' 100% with examples and a pointer to list_starters for discovery. The description adds no further parameter-level detail beyond saying 'by slug', so the baseline 3 for high schema coverage applies.

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 uses a specific verb ('Fetch') and resource ('full HTML body, CSS, sampleData, and pageOptions for one starter template by slug'), clearly distinguishing it from siblings. It explicitly mentions the use case of understanding data shape before calling render_template_to_pdf, which separates it from rendering tools.

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?

The description provides explicit usage context: 'Use this when you need to understand the exact shape of `data` the template expects before calling render_template_to_pdf, or when you want to fork a starter into custom HTML.' It lacks an explicit 'when not to use' but the alternatives are implied through sibling mentions and the focused use cases.

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