Get Card Builder design principles

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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: it explicitly states it returns a static constant and makes no HA call. It stops short of describing output size or whether content is stable across versions.

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?

Front-loaded with purpose, then when-to-use, then not-for, then a returns list. The returns enumeration is fairly long but each item (hierarchy, state feedback, spacing, typography, colors, layout, badges, backgrounds, empty states, anti-patterns) is substantive. Slight verbosity in the final sentence.

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 zero-param read-only knowledge tool with an output schema already present, the description covers purpose, routing to the sibling, and a topic list of what the markdown contains. Nothing an agent needs to decide to call it is missing.

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?

Zero parameters, so per the rubric the baseline is 4. No param semantics are needed and the description correctly does not invent any.

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+resource ('Get the embedded UX design playbook for Card Builder cards') and immediately distinguishes itself from the sibling by clarifying it returns a static constant and makes no call to Home Assistant. An agent can tell exactly what this returns versus card_builder_recipe_guide.

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?

Provides explicit 'Use when' conditions (hierarchy, state feedback, spacing, typography, layout choices) and a clear 'Not for' exclusion routing the block-tree mechanics to card_builder_recipe_guide. The when/when-not/alternative triad is fully present.

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