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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds the practical behavior of saving the fetched content to the repo root, and clarifies the fetched artifact is a full DESIGN.md. No contradictions.

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?

Two sentences, front-loaded with the core action, then the content inventory and a direct usage directive. Every clause 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 one-parameter, read-only fetch tool, the description is complete: it states what is returned, what to do with it, and when to call it. No output schema is required because the content is described in prose.

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 sole parameter `id` is fully documented in the schema (coverage 100%) with an example and source for valid IDs. The description only reinforces that the tool is per-theme, without adding new parameter semantics, so baseline 3 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?

Statement 'Fetch the full DESIGN.md for one theme' names a specific action and resource, and the content list (semantic colors, shadcn tokens, typography, contrast ratios, rules) distinguishes it from sibling tools like get_theme_tokens and get_design_md_for_url, which serve different retrieval scopes.

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 an explicit call to action: 'Read this before writing any UI,' and explains the persistence step ('Save it at the repo root as DESIGN.md so it applies to every session'). It does not explicitly name alternatives or when not to use it, so it stops short of full alternative routing.

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