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

Annotations declare the safety profile (destructive, idempotent, openWorld, not readOnly), but the description adds what they cannot: the visible side effect that media may show late or blank during re-download, that bulk calls silently skip screens outside your reach, and the required `screen.edit` permission. That is exactly the extra context annotations cannot carry.

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?

Four short sentences, front-loaded with the action and effect, then the when-to-use, then the alternative, then the permission requirement. No filler or repetition of the title.

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?

Covers the mutation, its user-visible consequence, the fallback tool, bulk behavior, and the auth scope; an output schema exists so return values need no explanation. Nothing an agent needs to call this correctly 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?

Schema coverage is 100%, so the baseline is 3; the description goes beyond it by explaining the relationship between screenId and the bulk screenIds path and that out-of-reach screens in a bulk call are skipped rather than erroring. It stops short of restating the 200-item cap, which lives in the schema.

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 and resource ('Delete the content files stored on one screen or many') plus the downstream effect ('so the player downloads them again'), which is exactly the distinction an agent needs. It also implicitly separates itself from refresh_screen by contrast later in the text.

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?

Explicit when-to-use ('when a screen plays an old or damaged file') and an explicit preferred alternative with the reason it should be tried first ('try refresh_screen first, which keeps the stored files'). This is a textbook when/when-not/alternative statement.

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