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

Annotations already declare read-only, idempotent, and non-destructive hints. The description adds meaningful behavioral context by stating exactly what the 'full record' contains, which is more than the schema or annotations alone provide. No contradiction or missing side effects.

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?

One sentence, front-loaded with the action and identifier method, then a compact list of returned contents. No fluff; every word 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?

Although there is no output schema, the description enumerates the main ingredients of the full record (viewport variants, palette, fonts, tech stack, designer credit). This gives an agent enough to understand roughly what it will get. It could be slightly more explicit about error cases or structure, but it is sufficient for a single-parameter getter with annotations covering safety.

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 has 100% coverage for the single 'slug' parameter, so the baseline is 3. The description only says 'by slug' and adds no extra meaning beyond the schema's own example. No compensation is needed because coverage is already complete.

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 names a specific verb ('Fetch') and resource ('full record for one screen by slug') and enumerates the content fields (viewport variant, palette, fonts, tech stack, designer credit). This is distinct from sibling tools like search_screens or get_collection, so an agent can differentiate it without opening the schema.

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 phrase 'by slug' clearly implies when to use it: when you know the exact slug for a single screen. It has a clear usage context, but it does not explicitly mention alternatives or when NOT to use it, stopping short of a 5.

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