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

Annotations are minimal (readOnlyHint=false, no idempotency), so the description carries the burden. It discloses that an API key is needed, that it returns a slug and editor link, and that the design never changes. It does not mention side effects like overwriting existing templates or error conditions, but it provides meaningful behavioral context beyond the annotations.

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?

The description is compact and front-loaded with the core action, then adds usage guidance and return value. Each sentence earns its place, and it avoids redundancy with the schema. The structure is easy to scan and the information is well-ordered.

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 tool with nested objects and multiple optional parameters, the description covers the essential context: the API key prerequisite, the intended usage pattern, the return value (slug and link), and the guarantee that design stays unchanged. It does not detail error handling or specific output formats, but given no output schema, the description provides enough for an agent to call it 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 100%, but the description adds meaning beyond the schema by explaining that fields are optional ('Omit a field to keep the template's own text') and that the 'fields' object sets new defaults. This clarifies the semantics of the 'fields' parameter beyond its schema descriptions, helping the agent understand how to use it correctly.

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 clear verb ('Copy a preset into the user's account as a saved template') and identifies the resource (preset) and outcome (template usable by render_card and og_image_url). It distinguishes itself from sibling tools like render_card, list_presets, and og_image_url by focusing on the save operation, and it states the returned slug/link, making the tool's role 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?

The description gives explicit usage guidance: 'Do this once per design, not per image' and explains that after saving, every render only passes changing text. It also notes the API key requirement. It does not explicitly name alternatives or say when not to use it, but the guidance is clear enough for an agent to decide when to invoke it relative to siblings like render_card.

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